An anonymous reader writes: On June 29, Microsoft announced that Windows 10 was running on 350 million devices -- 50 million more devices than the previous milestone announced by Microsoft on May 5. While the company is expected to update the number of devices running the latest OS when it releases the Windows 10 Anniversary Update on August 2nd, NetMarketShare has decided to conduct some research on its own. According to its report, Windows 10 currently runs on a 21.13% desktop OS share. Meanwhile, Windows 7 continues to dominate the market with a 47.01% share, with Windows 8 and Windows 8.1 representing less than 10% of the PC market, and Windows XP representing 10.34%. While the market share of Windows 10 is all but certain to rise, it likely won't rise as fast as it did between May and June or June and July for example, as Windows 10 is no longer offered as a free upgrade for PCs running Windows 7 or Windows 8. Microsoft has even backtracked on its original statement that Windows 10 will hit one billion devices by mid-2018, saying last month that Windows 10 likely won't in fact make that deadline.