Check the websites for the schools you're interested in. Many of them post this information.
Regardless, because most MD/PhD programs don't take state residency into account, the accepted stats are remarkably similar for schools in the same tiers. So if you look at the accepted stats for say WashU, Penn, or Baylor (I have them all linked in the MD/PhD forum FAQs), you can take them to be roughly correct (GPA, MCAT, and acceptance rate) for top 20 schools. The thing that tends to separate the top applicants is amount and quality of research experience, which is harder to put a number on.
The only place they really seem to vary is in what percentage they grant interviews, what percentage they accept post-interview, and how many students matriculate who are extended acceptances. But you have to be careful on that last statistic, as many schools don't accept until you have sufficiently professed your love for them, thus skewing the accepted to matriculated ratio quite a bit.