Are African Americans really mostly “Nigerian”?

Last year 23andme’s research team published a major landmark study titled “Genetic Consequences of the Transatlantic Slave Trade in the Americas“. Arguably the largest DNA study to examine African ancestry in the Americas! Covering a wide span of the Afro-Diaspora, incl. also several thousands of African Americans. Highly interesting therefore. The research approach of this study consists of combining genetic data obtained from 23andme customers with Trans-Atlantic Slave Trade patterns. Which is practically the same approach I have been using ever since I started my AncestryDNA survey in 2013. This study by 23andme is even including Cape Verdean samples as a control group! Which is something I have done as well in all my research sofar.1 Since I have recently finished my survey findings based on 23andme results (2018/2019 version) it should be useful to compare notes.

23andme’s 2020 study

My own survey findings based on 23andme and AncestryDNA results

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Table 1 (click to enlarge)

This overview is showing the scaled African breakdown for the combined USA sample group (n=5785) featured in Micheletti et al. (2020). As well as for my own African American survey group (n=200). Despite smaller sample size actually very similar outcomes. Providing mutual corroboration. As can be seen “Nigerian” was clearly the most significant region. Going by group averages around 35%. Usually “Nigerian” is appearing as primary African category (162/200=81% in my survey). But even so “Nigerian” is still far from being predominant (>50%). Especially “Ghanaian, Liberian & Sierra Leonean” is also showing up as a substantial component. Furthermore regional scores indicative of Senegambian and Central African DNA are still considerable and nearly at 10%, on average. Making for an overall varied and rather balanced African breakdown. Do notice as well that around 20% of the African breakdown is falling in one of the “Broadly” categories!

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In this blogpost I will compare my own research findings (based on regional admixture) with 23andme’s study from 2020. In fact much of the data contained in 23andme’s study (based on the 2018 version of Ancestry Composition) is consistent with my own. As demonstrated above in Table 1. Which features the African breakdown for African Americans on 23andme (scaled to 100%).2 Despite smaller sample size on my part actually very similar outcomes. Providing mutual corroboration. The study’s main findings of lower Senegambian and higher Nigerian ancestry than expected for African Americans are in line with what I had already established in my 2015 survey. Based on AncestryDNA test results for 350 African Americans. As well as more recently in my 23andme survey. See also:

Within the remaining part of this blog post I will discuss the following:

  1. Why do so many African Americans have Nigerian ancestry?
    • Ancestral implications of “Nigerian” go beyond modern-day borders
    • Domestic Slave Trade from mostly Virginia spreading Bight of Biafra lineage
    • Lower Senegambian than expected because of less reproduction?
    • Substructure according to state origins
  2. African breakdown for other parts of the Afro-Diaspora 
    • Mostly in agreement with historical expectations
    • Overlap & differences with my own survey findings
    • Regional diversity and substructure
    • Confirmation of Upper Guinean Founding Effect?
  3. Discordances & limitations of 23andme’s study
    • Afro-descended samples taken from migrants underrepresent wider variation in countries of origin
    • Central African IBD disproportionately high when contrasted with regional admixture from Central Africa 
    • Sex-biased admixture: multiple & context-dependent historical narratives! 
  4. Exciting future prospects:  personalized 23andme results featuring African IBD specified according to ethnic groups Continue reading

23andme’s African breakdown put to the test: Afro Diaspora edition!

In the last couple of years 23andme has implemented several updates. Often beneficial for Tracing African Roots! Starting with the introduction of a new African regional framework in 2018. Finally providing a meaningful breakdown of West & Central African ancestry! Soon afterwards I started a survey of 23andme results among Africans as well as African Americans and other Afro-descended nationalities.1 Similar to my previous Ancestry surveys my main research goal has always been to establish how much these results on an aggregated group level can already (despite limitations of sample size and other shortcomings) be correlated with whatever is known about the documented regional African roots for each nationality. As well as to improve correct interpretation of personal results.

Two years ago in February 2019 I published the first part of my examination of 23andme’s African breakdown. Which was based on my surveyfindings for 173 African 23andme testers from 31 countries (see this blog post). My 23andme survey has been ongoing till 23andme’s update in October 2019.2 Because of other projects I have not been able to process my entire data-set earlier. But in this blog post I will at last present my main 23andme survey findings based on 889 results from 28 different countries across the Afro-Diaspora! Actually I have already analyzed these results in greater detail (incl. screenshots of individual results) on these pages:

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Figure 1 (click to enlarge)

A small selection of 23andme results from across the Afro-Diaspora.  Most of the outcomes are roughly corresponding with documented African roots  for each of my survey groups. Unrealistic expectations about “100% accuracy” as well as counter-productive obsessing about regional labeling should be avoided. Instead focus on what ever informational value you can obtain despite imperfections. Take notice as well how the additional Recent Ancestor Locations are on point!

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To summarize: I do indeed believe that 23andme’s African breakdown has passed the test! Although obviously there are several shortcomings to take into account. Based on both my African and Afro-Diasporan surveyfindings I find it quite impressive though that 23andme is often able to describe a person’s African origins in a meaningful regional framework. Which will usually quite closely correspond with either known genealogy or historical plausibility. The additional non-African scores and Recent Ancestral Locations actually reinforcing the robustness of 23andme’s predictions. In the remaining part of this blog post I will discuss the following:

  1. African Breakdown
    • Main outcomes
      • Upper Guinean Founding Effect for Hispanic Americans
      • Virginia’s African roots most impactful on African American overall genepool?
      • Meaningful differentiation between Anglo-Caribbeans, Dutch Caribbeans and Garifuna
    • Frequency of primary African regions
    • Historical plausibility
  2. Substructure
    • African Americans, Brazilians, Cape Verdeans, Haitians, Hispanic Americans, West Indians
  3. Continental Breakdown
    • Southeast Asian admixture indicative of Madagascar connection
  4. Recent Ancestor Locations:
    • Pinpointing African lineage
    • Cross-Diaspora connections
  5. Screenshots 
    • Distinctive results across the Diaspora
    • Similar results across the Diaspora
    • Underrepresented parts of the Afro-Diaspora
    • Hispanic results reflecting Upper Guinean Founding Effect
    • Partially Cape Verdean results

Continue reading

Slave Voyages: not only Trans-Atlantic but also Intra-American!

This blogpost is mainly intended to announce a major overhaul for one of the most important sections on my blog:

The page referred to above is now featuring new screenshots taken from the invaluable Trans-Atlantic Slave Trade Database as well as the additional Intra-American Slave Trade Database. Reflecting the current state of knowledge. I am convinced that the data contained on that page can be very educational and useful for anyone wanting to learn more about their African roots. Just as long as you keep in mind inherent limitations and inform yourself about the relevant context. This kind of aggregated information is probably most useful on a population level.1 But also for your personal quest it can provide you with a very valuable starting point! In particular in order to judge the historical plausibility of any DNA test results you may have received. Not only regional admixture or haplogroups but also African DNA matches. And even DNA matches from across the Afro-Diaspora!2

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Despite its limitations the Trans-Atlantic Slave Trade Database (TAST) is simply the most comprehensive and up-to-date resource available when wanting to look into Trans-Atlantic Slave Trade patterns. The website was updated in 2019. It now includes information about more than 36,000 Trans-Atlantic slave voyages! See also this recommendation by Henry Louis Gates.

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““If there were a Pulitzer Prize given for historical databases, the Transatlantic Slave Trade Database would win it, hands down,” says Gates, Alphonse Fletcher University Professor at Harvard.” (source)

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I myself have often relied heavily on the Trans-Atlantic Slave Trade Database as some sort of baseline. To establish historical plausibility within my ongoing research efforts on how personal DNA test results of Afro-Diasporans may already be in alignment with historical expectations. See also:

It can be very tempting to correlate slave trade records with population genetics or assumed ethnic/regional origins of Afro-descended populations. Given the absence of more straightforward information. But such an approach can hold many pitfalls. Even if the Slave Voyages database is deemed to provide nearly fully coverage for any particular country. This is because you cannot just simply assume that there will be a direct extrapolation from the data at hand. Reality is too complex regrettably. Several factors need to be taken into account. Mainly to do with incomplete knowledge about the demographic evolution of enslaved Africans and their descendants. See the updated section for more detailed discussion. This aspect might be most pertinent:

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  • Intra-American Slave Trade, Domestic overland Slave Trade and Post Slavery migrations have resulted in great deal of additional intermingling and diversification of African lineage. This is especially true for the USA and Brazil because of their continental size. But in fact also for most parts of the Caribbean and Latin America.

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Table 1 (click to enlarge)

Based on these estimates (taken from O’Malley, 2009),  Intra-American Slave Trade for North America was around 15%. The actual shares per state do show important variation. For Virginia and South Carolina this share of slave trade by way of the Caribbean is  quite minor: around 10%. However for other states it is more substantial. Do keep in mind though that Domestic (overland) Slave Trade is not taken into account. While actually going by sheer numbers this type of Slave Trade was most significant for the USA. An estimated 1 million enslaved African Americans (often with Virginia background) are known to have been victimized by the so-called Second Middle Passage (see this link).

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Obviously there will be other factors as well that could explain genetic results being disproportionate to what you might expect based on slave trade data. Substructure within any given Afro-descended population also being highly relevant. This is something which I have blogged about several times already and also in upcoming blog posts I will return to this important topic. Within the remaining part of this current blog post I will discuss the following:

  1. Trans-Atlantic Slave Trade Database
    • Newly added Portuguese & Spanish Slave Voyages (1500’s) corroborate Upper Guinean founding effect for many Hispanic Americans
  2. Intra-American Slave Trade Database
    • Disclaimers
    • Intra-American Slave Trade Patterns for the USA
  3. Final Passages: The Intercolonial Slave Trade of British America, 1619-1807 (G. E. O’Malley, 2014)

Ancestry’s 2019 Update: Back on Track Again?

Backontrack

Map showing all the regions available on Ancestry after its 2019 update. For Trans Atlantic Afro-descendants the most impactful changes seem to be that: “Nigeria” has been brought back to life again! But “Ghana” has been derailed. “Mali” is no longer overpowering “Senegal”, but it does include both Sierra Leone and Liberia now! See this link for a complete list of regions and genetic communities. Photo credits for top picture showing a train passing by a railway station in Ghana.

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Starting in October 2019 Ancestry has been rolling out a new update of their Ethnicity Estimates. As I have said before your DNA results are only as good as the next update. So it is best not to get too attached to them 😉 Given scientific advancements and a greater number of relevant reference samples one always hopes that a greater degree of accuracy may be obtained. But naturally no guarantees are given that this will indeed be the case. After all Ancestry’s update in 2018 arguably was a downgrade rather than providing any meaningful improvement! At least when it comes to the African breakdown. In regards to the European, Asian and Amerindian breakdown Ancestry seems to have made steady progress on most fronts. Continued also with this 2019 update.

From my experience the best indication of predictive accuracy is obtained by looking at how Africans themselves are being described when tested by Ancestry. Which is why I have performed a comprehensive survey among 136 African Ancestry testers from all over the continent to establish a more solid basis for judgement. In addition I have also looked into a representative array of 55 updated results from across the Afro-Diaspora. These findings will be described in greater detail further below. The outcomes are mostly positive for Africans themselves but more ambivalent for Afro-descendants. Probably because Ancestry’s algorithm is less adequate when describing the mixed and therefore more complex African lineage of the Afro-Diaspora. My overall verdict about this 2019 update: a step in the right direction but no substantial improvements for the most part. At least not when compared with the original African breakdown from the 2013-2018 version.

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Table 1 (click to enlarge)

Stats Afro

Based on the updated results for 121 African AncestryDNA testers from 30 countries, across the continent. Take notice that the predictive accuracy in most cases is quite solid. Although in a few cases it is still clearly in need of improvement. This goes especially for “Ghana” and “Eastern Bantu”. Follow this link for my spreadsheet containing all the individual results.

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Due to wild fluctuations in just two years many people might experience update fatigue. Some people will even be tempted to bash their DNA test results and admixture analysis in particular. But an overtly dismissive stance will be self-defeating and deprive you of informational value yet to be gained! As I have always argued that regional admixture DOES matter and Ancestry’s Ethnicity Estimates are of course NOT randomly determined.1 Ancestry’s predictions may not be 100% accurate but still in most cases they are reasonably well-aligned with the known backgrounds of my African survey participants. As can be verified from the overview above.

For those perplexed by all the changes do at least make an attempt to inform your self properly. Given how wrong Ancestry got it in 2018 (see this blog series) it is only natural that some grave flaws had to be rectified. Regrettably it seems in some aspects an over-correction did take place. Still depending on your background this update certainly also can be beneficial. Furthermore when considering your African breakdown in a macro-regional framework the changes have actually not been that drastic. And many things more or less remained consistent as I will discuss in section 3 of this blog post.

It has always been my belief that regional estimates require correct interpretation. And each updated version as well as each separate DNA testing company should therefore be judged on its own terms. Then again these admixture results can only take you that far. My advise is to also look into your African DNA matches, as well as historical plausibility and just plain genetic genealogy for greater combined insight. See also these links:

For those seeking deeper understanding of Ancestry’s 2019 update this blog post will attempt to take things further by having a closer look at:

  1. African breakdown for Africans before and after the 2019 update
  2. Ancestry’s Reference Panel & Algorithm
  3. African breakdown for Afro-descendants before and after the 2019 update
  4. Getting back on track again
  5. Screenshots of African updated results
  6. Poll on whether this update has been an improvement or not, please vote!

Continue reading

100 Jamaican AncestryDNA Results (2013-2018)

On 9 October 2015 I published my first preliminary findings based on 19 Jamaican AncestryDNA results (see this link). Right now, four years later, I have managed to collect a sample group which is five times greater! Consisting of no less than 100 AncestryDNA results of Jamaican-born or fully Jamaican descended persons.1 Although still limited this data-set already provides a rather robust basis. Allowing for a finer detailed analysis of Jamaican genetics. In the first place with regards to the African regional roots of Jamaicans. But in addition I will also cover the Amerindian, Asian and European admixture scores being reported for Jamaicans on Ancestry. As well as variation in African admixture in general. With a special focus on substructure.

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JAMDNA

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These results were obtained during 2013-2018 but I had not fully processed all the data up till now. Although actually in 2018 I already blogged about this survey group (n=100) in my comparison of various parts of the Afro-Diaspora:

Please keep in mind that AncestryDNA’s ethnicity estimates have been updated several times now! In this blog post I am dealing exclusively with AncestryDNA version 2 which was current between September 2013 and September 2018. All matters being discussed are therefore not pertaining to recently updated results (2018/2019) (unless mentioned so specifically). In my opinion especially version 3 (Sept 2018 – Oct. 2019) has been a downgrade rather than providing any meaningful improvement when wanting to learn more about one’s African origins (see this blogseries). The update which is currently rolled out will be reviewed at a later time.

I will mainly revisit and expand on previous findings. Using new statistics and background information. Furthermore I will present my preliminary 23andme survey findings for 28 Jamaicans. This blog post is also intended to be a prelude for my current research into the African DNA matches being reported for Jamaicans. Which will be featured in a follow-up post to this one. Below an overview of all the topics I will cover:

  1. African regional breakdown in line with expectations?
  2. Variation & substructure in African admixture levels
  3. European breakdown reflecting mostly British ancestry
  4. Asian admixture: more or less widespread than imagined?
  5. Traces of Amerindian admixture is proof of enduring Taino legacy?
  6. Comparison with 23andme results being reported for Jamaicans
  7. Current update of AncestryDNA’s Ethnicity Estimates 
  8. Screenshots of individual results & Youtube videos

Follow these links for my complete survey data & research methodology:

Table 1 (click to enlarge)

Macro

This table features an additional breakdown of my own making into 3 greater macro-regions: “Upper Guinea”, “Lower Guinea” and “Central Africa” (also includes Southeast Africa). I find this distinction useful because it allows certain regional patterns to show up more clearly. In particular it seems apparent that the bulk of Jamaica’s African roots are from the area in between Ghana and Nigeria (=Lower Guinea).

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Table 2 (click to enlarge)

Cont. breakdown JAM

The continental breakdown is often considered to be the most reliable within admixture analysis. Aside from reviewing the group averages it is recommendable to look into other statistical measures as well. As many people tend to have misconceptions on how “typical” their personal results might be. Compare also with my 23andme surveyfindings (n=28), see this table.

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Continue reading

Update: Afro-Diasporan AncestryDNA Survey (part 2)

In May 2016 I published the first summary of my Afro-Diasporan survey findings based on 707 results for 7 nationalities (see this blog page). My survey has been ongoing ever since. Right now an update of AncestryDNA Ethnicity Estimates seems even more imminent than it was in 2016 (when it was canceled in the beta phase). So that’s why I will yet again provide a “final” overview of my survey findings 😉 See this link for the first part of my findings which is focused solely on the African breakdown:

In order to provide a broader perspective on the complete DNA make-up of Afro-Diasporans I have this time also analyzed the non-African regional scores on AncestryDNA. Enabling a continental breakdown for my 8 sample groups. Mainly based on 860 results for people from 8 nationalities1. Although the total number of results and nationalities in my survey is even greater.

Generally speaking also the non-African group averages seem to be reasonably in line with historical plausibility. Amerindian, Asian and Pacific trace-amounts are not being left out. These scores are often labeled as low confidence regions and dismissed as just “noise”. Rightfully so in some cases. But given correct interpretation and proper follow-up research at times these scores can still potentially lead you to distinctive ancestors. Furthermore my survey results are now also allowing for a more detailed discussion of the European breakdown as being reported for Afro-Diasporans.

I would like to underline right from the start that my findings are not intended to represent any fictional national averages! The group averages I have calculated for my sample groups are neither absolute or conclusive but rather to be seen as indicative. Obviously several shortcomings may apply. One main aspect to take to heart is that there will always be individual variation around the mean. Given correct interpretation I do believe these group averages suggest insightful tendencies though for each of my 8 sample groups. They also mostly comply with the findings of admixture studies published in peer reviewed journals, or at least the ones I am aware of.2

Chart 1 (click to enlarge)

Continental breakdown

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Continue reading

Update: Afro-Diasporan AncestryDNA Survey (part 1)

In 2013 AncestryDNA updated their Ethnicity Estimates to include a detailed breakdown of West African DNA. Pioneering when compared with other DNA testing companies. Soon afterwards I started collecting AncestryDNA results in an online spreadsheet in order to conduct a survey of the African regional scores being reported by AncestryDNA. At first only for people of the Afro-Diaspora and later on also among Africans. My main research goal has always been to establish how much the AncestryDNA results on an aggregated group level can already (despite limitations of sample size and other shortcomings) be correlated with whatever is known about the documented regional African roots for each nationality. As well as to improve correct interpretation of personal results.

In May 2016 I published my first summary of my Afro-Diasporan survey findings based on 707 results for 7 nationalities (see this blog post). My survey has been ongoing ever since. Right now an update of AncestryDNA’s Ethnicity Estimates seems even more imminent than it was in 2016 (when it was canceled in the beta phase). So that’s why I will yet again provide a “final” overview of my survey findings 😉 . Mainly based on 1,264 results for people from 8 nationalities. Although the total number of results and nationalities in my survey is even greater.

A major addition is the inclusion of 45 Brazilian results. Their predominant Central African profiles (as measured by both “Southeastern Bantu” and “Cameroon/Congo”) are quite striking when compared with my other sample groups. This outcome reinforces how the African breakdown on AncestryDNA has been reasonably in alignment with historically documented origins of the Afro-Diaspora. Unlike any other DNA testing platform I’m aware of and therefore not to be lightly dismissed despite inherent imperfections.

In the second part of this blogseries I will also provide an overview of the non-African regions (Amerindian, Asian, Pacific etc.) being reported for Afro-Diasporans. As well as a more detailed analysis of their European breakdown.

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This frequency of regions being ranked #1 (regions with the highest amount in the African breakdown) is perhaps the best indicator of which distinct African lineages may have been preserved the most among my sample groups.”

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Chart 1 (click to enlarge)

Afro piechartsa

Continue reading

DNA matches reported by 23andme for 75 Africans

Wishing to share the vibranium 😉 I have created a new page featuring the DNA matches reported by 23andme for 75 Africansall across the continent. These results were collected by me in 2015 when 23andme’s Countries of Ancestry (CoA) tool was still available.

My survey results might have limitations in several regards but I do believe these African CoA results can still reveal relevant tendencies in DNA matching. I intend to compare these preliminary matching patterns eventually with my more recent findings for Africans who tested on Ancestry. I provide detailed background info as well as screenshots of the individual results on this page:

(click to enlarge)

Continue reading

“Benin/Togo” also describes DNA from Ghana & Nigeria

I have created a new page featuring the AncestryDNA results for West Africans from the following countries: Liberia, Ivory Coast, Burkina Faso, Ghana, Togo & Benin. I will create a new section for the remaining part of West Africa (Upper Guinea) shortly. The number of results I have collected so far might be minimal but already my survey findings turn out to be quite insightful. I also provide some statistical data, analysis and relevant context. Follow this link to view the page:

In addition I also discuss the implications these findings might have for Afro-Diasporans in an attempt to improve proper interpretation of their West African regional scores, in particular for “Ivory Coast/Ghana” and “Benin/Togo”. One of these implications I will also discuss in greater detail in this blog post:

“Benin/Togo” is also predictive of Ghanaian & Nigerian DNA

The so-called “Benin/Togo” region seems to be quite predictive of Beninese origins (based on two results). However in addition ancestry from eastern Ghana and southern Nigeria might also be described by this region. You will need to perform your own follow-up research in order to find out more specifics.

Map 1 (click to enlarge)

Benin Togo

Source: ancestry.com

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Chart 1 (click to enlarge) 

Stats (GH=22)

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Continue reading

“Ivory Coast/Ghana” also describes Liberian DNA

I have created a new page featuring the AncestryDNA results for West Africans from the following countries: Liberia, Ivory Coast, Burkina Faso, Ghana, Togo & Benin. I will create a new section for the remaining part of West Africa (Upper Guinea) shortly. The number of results I have collected so far might be minimal but already my survey findings turn out to be quite insightful. I also provide some statistical data, analysis and relevant context. Follow this link to view the page:

In addition I also discuss the implications these findings might have for Afro-Diasporans in an attempt to improve proper interpretation of their West African regional scores, in particular for “Ivory Coast/Ghana” and “Benin/Togo”. One of these implications I will also discuss in greater detail in this blog post:

“Ivory Coast/Ghana” is also predictive of Liberian & Sierra Leonean DNA

The socalled “Ivory Coast/Ghana” region is indeed quite predictive of both Ghanaian and Ivorian origins. However in addition ancestry from Liberia and to a lesser degree (southern) Sierra Leone might also be described by this region. You will need to perform your own follow-up research in order to find out more specifics.

Map 1 (click to enlarge)

IvcGhana region

Source: ancestry.com. (text in red added by myself)

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Chart 1 (click to enlarge) 

Stats (GH=22)

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