it's a Gaga single. all the stans are drooling for that #1.
but I agree with you, considering the year as a whole, it really didn't do so bad. I'd like to point out that it remained for a very long time her #1 scrobbled song per week on LastFM, and still is pretty up there. It is an amazing song and anything who owns the album knows it, regardless of its success as a single.