Hopefully the data here only consists of desktop Linux users. If it includes SteamOS users then it kind of skews the data…
Edit: Jesus, so much hostility right off the bat. Chill the fuck out people. I don’t hate Linux and I’m not even upset. I’m talking about statistics—it says “on Steam”, and thus any data that is by definition a part of Steam is a form of statistical bias. It’s a part of Steam, so of course it’s going to be “on Steam”. It skews the reliability of the graph.