According to this I've contributed about 0.004% of the content on OSM since I started about three years ago. That's 1/25,000 of all the content.
I'm sure that I could have done more, and perhaps I ought to feel bad about that. But I don't. This isn't a competition (or if it is, I'm not playing). There are 336,650 registered OSM users. I'm quite pleased with the bits I've added, but more than 2,000 have made a bigger contribution than I have, and I think that's great.