The venerable and esteemed IEEE Spectrum has an interactive chart for ranking computing languages. The references that they use are Google searches/trends, Twitter, GitHub, Stack Overflow, Reddit, etc.
These comparison charts are always valuable, but they also introduce new questions. For instance, why does the IEEE data differ so much from RedMonk's own listing of programming languages ? Sure, the reference sources are a bit different, but Objective-C or Shell scripts have dramatically dissimilar rankings between the two summaries. Redmonk only pulls data from GitHub and Stack Overflow, so it's now apparent that their programming choices are not universally applicable.