Yes, that is alarming. But if you understand the history of this country, it isn't as shocking. You have a population considered non-human for centuries. And not even at least somewhat of an equal legal standing until the 1960s. Heck, my mom was born then. Do you think that after all of that, everyone can just get over it in 20-30 years?
Boston schools busses weren't desegregated until the 1970s. And despite the Civil Rights act, there are still many documented and provable issues with equal access, inequality, poverty, justice system issues(school kids being sold into the prison system as an example), etc. Taking that all in, it's not shocking to see that that minority population is not represented well in these stats.
Sure some people overcome even all of that, but they are still unique issues that nobody else has to deal with.
Edit: Another thing that really helped the country is a couple centuries of free labor.