Publications don't "post" their scores there, it's Metacritic that collects scores from the publications they judge credible enough. Admittedly, their methods are less than transparent, but the logic behind that choice (instead of, you know, aggregating all reviews they can find and do an average) is pretty sound.
GameRankings offers some pretty similar scores anyway, 74,60% for PC, 74,06% for the Xbox 360 and 74,21% for the PS3.