http://blog.okcupid.com/index.php/your-race-affects-whether-people-write-you-back/?a=1

White women prefer white men to the exclusion of everyone else—and Asian and Hispanic women prefer them even more exclusively. These three types of women only respond well to white men. More significantly, these groups’ reply rates to non-whites is terrible. Asian women write back non-white males at 21.9%, Hispanic women at 22.9%, and white women at 23.0%. It’s here where things get interesting, for white women in particular. If you look at the match-by-race table before this one, the “should-look-like” one, you see that white women have an above-average compatibility with almost every group. Yet they only reply well to guys who look like them. There’s more data on this towards the end of the post.

More interesting facts on the link.