The way you phrased the question makes it really difficult to answer.
Schools initially accept more students than matriculate. Schools in the top 5 like UPenn or Harvard initially accept only a few students more than their class size (because it's less likely for people to turn those schools down). In addition these schools pull far less students off the waitlist than a third teir school would.
The answer to your question depends where you get the stats from. If you ask a school how many people they initially accept, they'll generally tell you. However, if you're reading AMSAR and you get the stats from there, then the number accepted includes those pulled off of the waitlist.
I think the number accepted on the USNews rankings also includes people pulled off the waitlist(at least thats what someone said on an earlier thread so I don't know for sure). But since those people pulled off the waitlist are also given "acceptance latters" it makes sense to include those people in the "number accepted stats."