All I can find is the "TIOBE Programming Community Index."
You might as well not bother. TIOBE is excessively vague about what it measures to the point that no one's been able to reproduce its results. Worse, it's never demonstrated that the number of searches it measures has a strong correlation with usage.
Worst, it confused the Google Chrome browser with an implementation of Pascal for quite a while.
Agreed. The thing is, I can't find anything better, so such questions as "when did the popularity of language X peak?" seem unanswerable.[1] We are left with anecdotal impressions, and my own experience ;) says that those are even more suspect than TIOBE's numbers.
Also, I was looking for popularity, not usage, although these two numbers are intertwined and hard to disentangle.
[1] That's not quite true. http://langpop.com/ for example has what appears to be a more well-defined method of accumulating that data. However, "Last data update: Wed Apr 13 14:57:11 +0200 2011", the operator is no longer interested in the project, and would like to sell the site. I cannot find trend data, and my guess is that that's reserved for whomever will buy the site. So it might be answerable if I want to spend money on it.
You might as well not bother. TIOBE is excessively vague about what it measures to the point that no one's been able to reproduce its results. Worse, it's never demonstrated that the number of searches it measures has a strong correlation with usage.
Worst, it confused the Google Chrome browser with an implementation of Pascal for quite a while.