I cannot say exactly how many hours I have PLAYED.
I do leave the game running from time to time when I am farming ships and take a break from my other duties in the galaxy and blow up a few rebels now and then.
I can easily say that this is the game that I have played the most in 2012 and probably will play the most in 2013 though!
I've played at least 30 hours on easy; then reset the scores and started on normal. As for normal, that would be around 47 hours of play. I sometimes do leave the game open for 10 minutes or so while doing other things, but that accounts for maybe 2 hours.
Sometimes I think I'm burning myself out on this game, luckily modships are around.