Because I have things I'm meant to be doing instead but which are dull, I just went through all the stories since Rose. A couple don't really state when they're set, and occasionally they're set in multiple times, but here's the breakdown:
Past: 30.6%
Present: 34.1%
Future: 30.6%
Unknown: 4.7%
That's a pretty even split, to be fair.
Here's the thing, though. Sometimes, episodes are set in the future purely to allow the premise.
If you're going to have a story about human colonists on a spaceship, or about the end of the world, or man's exploration of other planets, then by definition they have to be set in the future. But the story itself may end up being fairly timeless ... e.g. Midnight is set in the future, but that's just to set the scene - it could just as easily have been set in any closed vehicle in any inhospitable environment in any time.
The other problem with future episodes (and I say this as someone who also enjoys them) is that they don't give viewers something as recognisable to identify with. Historical and present episodes are fun because we get to put the Doctor into settings/events that we know about, and then play with that, e.g. his interactions with Shakespeare in The Shakespeare Code, etc.
It's more fun to believe that the Doctor influenced a past event than it is to imagine that he will influence an event which a writer has forseen.