“I cannot say how many candidates accepted graft...”
You don’t seem to understand; what you call “graft” was strictly legal.
Someone ran the numbers; his contributions to Republicans were slightly more than to democrats.
Pay for play, Quid Pro Qou, cronyism may all be "strictly legal but so is killing children, running a deficit, and K street lobbyists writing bills and donating to political campaigns. The question is not if an action is "strictly legal" but if it is moral and right. I am not all that interested in a more effective corruption, but in the elimination of it.