This graph shows the market share of desktop operating systems worldwide based on over 5 billion monthly page views.
It peaked at 4.05% in March. The last 2 months it went just below 4% as the Unknown category increased. For June the reverse happened, so 4.04% seems to be the real current share of Linux on Desktop as desktop clients were read properly/werent spoofed.
Based on a world population of 8 billion, that would be roughly 0.000000000000008% of a person. It's also not even representable as a 64 bit float so I had to do this math in my head (Calculator just says 0)
What's interesting is that multiple trackers are now saying it's above 4 percent. Last time something was posted, people questioned the data and where they got their data (which they should). Now there's multiple sites showing a real increase.