May was the seventh full month of availability for Microsoft’s latest operating system version: Windows 8.1 continues to grow slowly while Windows 8 remains largely flat, allowing the former to finally pass the latter in market share. At the same time, Windows 7 has managed to climb back over the 50 percent mark, while Windows XP still has more than 25 percent of the pie, despite support for the ancient OS finally ending in April.

The latest market share data from Net Applications shows that Windows 8 and Windows 8.1 have gained a combined 0.40 percentage points (from 12.24 percent to 12.64 percent). More specifically, Windows 8 slipped 0.07 percentage points (from 6.36 percent to 6.29 percent), while Windows 8.1 grabbed an additional 0.47 percentage points (from 5.88 percent to 6.35 percent).

Windows 8, which saw its biggest gain in August at 2.01 percentage points and its biggest loss in November at 0.87 percentage points, continues to slip. There are still computers being sold with Windows 8, but Microsoft is encouraging the upgrade path to Windows 8.1 by making it just a free download away for Windows 8 users.

Meanwhile, Windows 7 managed to grab an additional 0.79 percentage points (from 49.27 percent to 50.06 percent). Windows 8 and Windows 8.1 usually do better combined than Windows 7 does, but some months the opposite happens, and May was one of those instances. It should surprise nobody if Microsoft ends up struggling to woo users off Windows 7 one day, just like the current headache it is experiencing with Windows XP.

Going back to earlier versions, Windows Vista managed to gain 0.01 percentage points (from 2.89 percent to 2.90 percent). Windows XP meanwhile dropped a solid 1.02 percentage points (from 26.29 percent to 25.27 percent). Unfortunately for Microsoft, that drop is nowhere near as large as it should be.

In 2013, Windows lost share every month except for March, July, and November. So far in 2014, Windows slipped in January and April, gained in February and March, and now gained 0.19 percentage points (from 90.80 percent to 90.99 percent) in May. OS X fell 0.23 percentage points (to 7.39 percent), while Linux gained 0.04 percentage points (to 1.62 percent).

Net Applications uses data captured from 160 million unique visitors each month by monitoring some 40,000 websites for its clients. StatCounter is another popular service for watching market share moves; the company looks at 15 billion page views. To us, it makes more sense to keep track of users than of page views, but if you prefer the latter, the corresponding data is available here (mobile and desktop operating systems are combined).

Top Image Credit: Mario Tama / Getty Images

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