I'm sure PG could break down those numbers for you, but they wouldn't be meaningful. Yes, people from "better" institutions are more likely to be accepted; but that doesn't tell you whether it's the institution which matters or simply that those were the better students to begin with.
The proportion would certainly be interesting. i.e. 90/5/3/2 wouldn't surprise me but if it was more like 40/30/20/10 I would definitely be interested in knowing that.
