I can't really find any all time stats for any conference. Seems like it would be easy info I guess not. It also shows the big 12 has a better record in the sweet 16 and beyond.
It is a smaller window though
http://aol.sportingnews.com/ncaa-basketball/story/2012-03-14/ncaa-tournament-2012-michigan-state-ohio-state-michigan-wisconsin-indiana