Windows 8.1 use is growing slowly and overtaken Windows 8 sales, which have been flat as a pancake. The latest market share data from Net Applications shows that Windows 7 has managed to climb back over the 50 percent mark, while Windows XP still has a quarter of the pie.

The Net Applications findings have Windows 8 and Windows 8.1 gaining a combined 0.40 percentage points, from 12.24 percent to 12.64 percent. 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 saw its biggest gain in August at 2.01 percentage points and its biggest loss in November at 0.87 percentage points. It has been slipping ever since. There are still computers being sold with Windows 8, but Microsoft is giving away a free upgrade which makes the older software less popular.

Meanwhile, Windows 7 managed to grab an additional 0.79 percentage points, from 49.27 percent to 50.06 percent.

Windows Vista managed to gain 0.01 percentage points, which seems unlikely, and Windows XP meanwhile dropped a solid 1.02 percentage points. That drop should be much more, given that Microsoft is not supporting the software anymore.

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).