I have to take exception to the characterization above. Much of the support for the claim is the "fact: that a larger percentage of these people are actually in prison.
Perhaps that is because more crimes are actually committed by these groups.
Now I know I do not have data. While I was refilling my tea I thought about the data. It has to exist somewhere but I have to devlop the question to ask in order to find it.
I have to find data on arrests vs convictions somehow.