On can always look at average numbers, though they don't tell the whole truth they are a good guidance.
I met a guy at MIT Sloan with 38 (I may be wrong, but it was around that), and I know one here at Chicago Booth with 36 - talking about FT programs. That said, both are willing to open their own business.
I believe that up to 33 people would have a shot to many places, though historically, H/S are the ones that things get harder - but we have terry's example here that with 30 one can break into Stanford GSB.
About the schools you mentioned I believe that Columbia would be the hardest (CBS also seem to be moving a little bit towards younger applicants from what I've hard from some friends of mine who are there), but all of them, especially this year, will be hard.