Earlier quoted context omitted.
Came to say exactly this. The chart seems to start (by default anyway) at the beginning of 2007. I'm guessing the user-base and thus activity of HN has increased considerably since then. So yes it would be good to be able to re-normalise in some way. By the number of registered users would probably be the simplest. By number of comments posted would be another, by number of submissions or even number of words would a…
It uses submission titles AND comments. How would you suggest going about normalization?
Your app looks a lot better, though! (And my dataset ends around Sept. of last year.)