I think it really depends on what you are playing (limit/NL) and what the blinds are, is this a tournament or a straight game?

In a tourny I'm going to see a lot more flops early on when they are cheap than I will later on as they get more expensive. Same thing if it's a Limit game and I can get in cheap with an ok opening hand.

In a NL tourny overall I'll probably see under 20% when it's all said and done.