(How'd you calculate that, by the way? Just eyeballing, or is there a page?)
(Just eyeball... on further reflection it may be more like 80th percentile. I know that on Hacker News, the karma distribution is exponential with a quick fall-off and I expect the distribution here is very similar.)
Some research says that lurkers make up over 90% of online groups. I suspect that Less Wrong has an even higher percentage of lurkers than other online communities.
Please post a comment in this thread saying "Hi." You can say more if you want, but just posting "Hi" is good for a guaranteed free point of karma.
Also see the introduction thread.