Where is it you see this number of hours? I've not bothered to actually look, I've been far too engrossed in the game.
Oh, actually on thinking about it, the steam library page will tell you, won't it? I put a desktop shortcut for it instead so haven't visited the page. At most I'd say I've done about 30 hours though since Christmas, only at level 23.
Just started the Thieves' Guild quests, and enjoying my sneaking skills being OK. I shot a guy in the back with a bow, then hid in a corner. He runs straight past me, stops in front of me and I started to panic. Then he states to his friends that it must have been nothing and wanders back to his friends, with an arrow still sticking out of his neck.
Rinse and repeat.
Unfortunately this means that bringing Lydia along is a no-no, she's far too trigger happy and willing to charge into action. I miss the extra carrying capacity she brought to the table though.