It's highly skewed towards the young, who just might be more likely to mouth the politically correct answer to survey questions, not that that's the entirety of the dataset they use.
Steve Sailer looked at this issue more than a dozen years ago. ) Granted, he left non-Caucasian whites (i.e., latinos) out of his analysis, but he still made an interesting observation by including Asians rather than following the customary procedure of just making it a black/white thing.
We tend to seek out our own "type" and for educated women or women of a diverse decent, White males are usually the pick because they meet the standards (most of them, not all) of these types of women. might I add that although most White men identify as "White," they are sometimes a mixture of a multiplicity of cultures.
This also makes them a more attractive candidate because of style, ideologies, and the like.
"All the asian girls are with white guys, all the white girls are with black guys, the asian guys come together and the black girls are alone." Racist? I'm not sure I agree that skin color is a pre-requisite for certain daters.