Desktop Operating System Market Share Worldwide | Statcounter Global Stats
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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.