How often are you NOT called when raising PF?

I play 9max on the stars: $25 and $50 games.
I find that when playing tight preflop, playing approximately 20% of hands and raising roughly 7-9% of them, that many of times I am not getting called by raising a standard 4BB+1BB for each limper. Everyone folds to me about 40-50% of the time... it gets especially frustrating when holding AA and KK in early position.