Makes sense. These are the stats for the Humble Jumbo Bundle 5 which has only one Linux game, Insurgency, which is brand new on Linux. I assume lots of people are going to want it but they’re not going to bother paying above average for a bunch of (unknown, at least for me) Windows games.
I might reconsider next week when new games are added, but unless they add some pretty good stuff, I’m not going to bother with this one, even to make Wine scripts for Lutris.
For the latest Humble Indie Bundle, Linux users still paid more than Windows and Mac (http://cheesetalks.net/humble/#Indie%2015)