Africans - account for about 1% of US Phds in STEM topics.
“African” Americans - account for about 1.5%.
You are correct - it is very obvious at the top end.
I forget the study - but it is somewhere about Phds grantd to minorities. Africans are counted as minorities - although they are foreign. So - you have to cross reference a few tables - to subtract out the Africans from the Afri-Americans.