A year and a half after its release, Windows 10 has passed 25 percent market share. That means one in four computers are now running the latest and greatest operating system from Microsoft, according to Net Applications.

Windows 10 was installed on over 75 million PCs in its first four weeks, passed 110 million devices after 10 weeks, 200 million in under six months, 270 million after eight months, 300 million after nine months, 350 million after 11 months, and 400 million after 14 months. Microsoft was aiming for 1 billion devices running Windows 10 “in two to three years,” but backpedaled on that goal.

Windows 10 had 24.36 percent market share in December and gained 0.94 percentage points in January to hit 25.30 percent. Windows 10 market share growth slowed over the second half of 2016 because the free upgrade expired.

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Windows 8 slipped 0.04 percentage points to 1.62 percent, while Windows 8.1 stayed flat at 6.90 percent. Together, they owned 8.52 percent of the market at the end of January. The duo’s peak was 16.45 percent back in May 2015.

Windows 7 ended 2016 at 48.34 percent, but has fallen to 47.20 percent as of January. Windows 10’s slice of the pie is thus now slightly more than half of Windows 7’s, which is likely keep its title of “most popular OS” for a long time. Windows 7 overtook Windows XP way back in September 2012, and passed the 60 percent market-share mark in June 2015.

Windows Vista dropped 0.22 points to 0.84 percent, falling below the 1 percent market share mark in the month of its 10-year anniversary. Windows XP somehow rebounded 0.10 points to 9.17 percent as its resilience continues to annoy Microsoft and the general tech community.

Overall, Windows slipped 0.31 percentage points to 91.41 percent in January. Mac OS X gained 0.25 points to 6.32 percent and Linux gained 0.06 points to 2.27 percent.

Net Applications uses data captured from 160 million unique visitors each month by monitoring some 40,000 websites for its clients. This means it measures user market share.

If you prefer usage market share, you’ll want to get your data from StatCounter, which looks at 15 billion page views every month. The operating system figures for January are available here.

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