There is now.
It's not pretty, and there might be mistakes in there, I'll have to review it later.
You have to input the year, otherwise the graph looks like a mess (and I'm bad with graphs).
And it probably needs a few less joins...
But it's fast enough right now for ServerFault.
Fun little first thing I noticed, if you look at each year, the 0-100 group used to be the minority, it has steadily grown to be the most active group on the site.
Meanwhile the 10000+ group has been slowly declining (all-be-it much slower).