I've returned maybe 3 wallets/purses to people. And a couple of cell phones. I don't know if that's higher than average, but I think I might have an eye for it.
One girl was more freaked out that I could find her phone number on the internet using the address on her ID card than she was thankful that I went through the trouble to return it and didn't steal any cash. She was odd. It would have been weirder (and more work) to knock on her door...I think, at least. Another guy hardly even thanked me, just took it and walked away.
The rest were cool though, even giving me money in return.
Ditto on the statistics commentary. (So yeah, the above isn't statistically significant, but it is my experience.)