Source
Linux currently 29.1%
Sample size according to StatCounter: 24,353,436 page views
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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This is reported as a percentage and that's what is tripping people up here.
You are not seeing a drastic rise in Linux usage you are seeing a large decrease in the use of desktop computers.
Linux is increasing because the only ones left using desktops are Linux users.
Nice explanation but here is a graph with desktop percentage included (versus mobile plus tablet, but that isn't shown)