Here’s an interesting chart, giving a realtime view of which programming languages have high mindshare. The chart has one axis devoted to number of lines in code commits on GitHub, and another to how often the language shows up in tags on StackOverflow.
I don’t think the chart is perfect. I’ve seen it billed as a “popularity index,” but I think it might be better described as a measure of how busy the coders are who use each language. If most of the coders who use a language hate it, I don’t think it’s fair to call it “popular.” Some apples-to-apples issues are glossed over, such as the fact that certain languages are very verbose, and some languages tend to get used mostly for “big” projects or for “small” ones. And the chart says nothing about the quality of systems built with the languages, or about the velocity of teams.