List the election years in which a member of the United States Electoral College did not vote for the presidential or vice-presidential candidate for whom they had pledged to vote. I've listed the number of faithless Electors in each particular election year and given the eventual election winner.
Not much. Maybe a fine. Some states make it illegal to be a faithless elector which carries a fine. Other states invalidate the vote, so it would be the same as abstaining.