If we're basing this on the hypothetical where a person had his choice before beginning the process, Harvard and Stanford will be sky high. Probably a smaller but still significant percent at Wharton. My gut says that maybe the Chicago schools will be somewhat higher than the rest and then probably a low percent at the other schools based on having a spouse or family nearby or other "real life" circumstances.
If you're basing it on where people have come to terms with their real profile, then my guess is that after HSW you're looking at a larger share as many people will start the mental process of making their realistic shots their first choice.
If you're basing it on asking people after they actually go, I'd imagine that it's pretty darn high at all the schools. ("If you knew what you know today, would your school be your first choice?")
That sounds cynical, but it's not. I think it's a good thing that people, armed with more information about not only the schools but themselves, will view where they are in the most positive light.