Please see my post 50 regarding cross racial rapes. While the fact that black on white crime was 85% of interracial crime might be explained by population statistics, its more a function of the large number of cross racial rapes committed by blacks (whites commit far more rapes).
Note that of black rapists, 41% of their crimes were cross racial, compared to 3% for white rapists. Thats far from statistically insignificant. If these were crimes of opportunity those stats would be similar for both groups.
let's try this one more time with the last of the mohicans. Let's say that there exists one guy who is the last of the mohicans and he lives in a town with 5000 whites. Let's say the mohican goes out and rapes someone and a white guy rapes someone. In this case, Note that of mohican rapists, 100% of their crimes were cross racial, compared to 0% for white rapists