> Assuming everyone who graduated with a CS degree from the US was hired at an equivalent then one would expect something closer to 7%-8%.

When I look at the data, I see that 2.5% of graduates are black. I'm looking at PhD, Master's or Bachelor's in CS in 2015.[1]

The totals exclude those with unknown ethnicity:

15 black CS PhDs out of 1442

110 black CS Master’s out of 8,923

425 black CS Bachelor’s out of 11,974

(15+110+425) / (1442+8923+11974) = ~0.0246

[1] 2015 Taulbee Survey, Computing Research Association

http://cra.org/wp-content/uploads/2016/05/2015-Taulbee-Surve...

EDIT: I believe one big source of the difference between our numbers is whether you count "Information" degrees as a CS degree. My number only looks at "Computer science" degrees, whereas your data looks at "Computer sciences" degrees.