I'd say 35-40 so far. I need to crank the difficulty up from Adept soon though, my two 292 damage enchanted war axes are chewing through EVERYTHING in 2 hits max. Max Smithing and Enchanting is so ridiculous
Spent four hours, didn't find a single dragon. 8 horus later and I've killed at least 14-15 and I'm barely into the main quest.
That comic should have had a last panel that said "After killing your tenth dragon you wonder if you have room for the bones, and whether it's even worth it."
I know that's cynical, and it rightfully is.
Skyrim is an amazing game, its brilliant, breath-taking, but by the time you find an orcish/dwarven war axe, you basically just wait for the dragon to land, and stab its wing just outta attacking-distance until it's dead...
I've killed two. The first main one that you're supposed to kill and another random one. The second one was awesome. I was walking into a town when all of the sudden I heard a roar. I look up, and there's a dragon flying over the town. The super guards immediately engaged it, as did everyone else in the town. The thing was torn apart. I got maybe two hits on it.
This apparently ticked the game off though, as not five minutes later I'm wandering in the middle of nowhere and another one lands on my head. Ran for the nearest cave and hid--and promptly got torn apart by Trolls. Good times.