That x-axis explained
Hi AndyS, your point is a good one. It's sloppy of me, but there's no attempt to deceive. The Linux x-axis was tricky to label because the data points are the releases. They have been pretty regular, so I spaced them equally. Either putting the release numbers or the dates seemed hard to read (but if anyone asks, I can put up a fully labelled version).
Roughly speaking, the x axis for the Linux graphs starts in 2005, finishes in 2012.