[BrianaB]

I'm assuming both players are of equal ability post flop. ie. best hand pre flop wins. (obviously sometimes a player will fold the best hand post flop, but this will even out because both players are equal post flop).

If BB folds 100% of the time you would obviously raise every single time.
If he calls 100% of the time (never re-raises) you should raise whenever ahead, according to the fundamental theorem. The button should therefore raise 49.9% of all hands. (is this correct?)
If there is no point where you add hands, this implies that you should never, against any opponent, raise less than 50% of the time, regardless of his preflop play (and still assuming equal ability post flop). Is this correct?