The proportion stayed low for about 20 years.
The "original sin" in 1976 was just one of many acts of legislation that were "compensating" for the Civil Rights reforms by cutting down the funding available to Black students.
It's amazing how little one has to peel in all things that suck in the US to find racism behind it. And now all of us are screwed.
[1]https://journals.iupui.edu/index.php/muj/article/download/20...