The last graph shows, of people who get stuck in vim what language they use the most. This means this could just be a graph of the most used programming languages. eg if there is a uniform 10% probability that anyone will get stuck in vim. I would find it interesting to see a graph that show what percent of each language's users get stuck in vim.
The latter is indeed what that graph is showing: what percentage of each language's users get stuck in Vim (or more precisely what % of their Vim visits are to that question). It's not being confused with the most used programming languages.
