Computerworld - https://www.computerworld.com/article/3199373/windows-pcs/windows-by-the-numbers-windows-10-gains-ground-but-still-trails-windows-7.html#tk.rss_all
Windows 10 last month for the first time passed the 40% milestone, but adoption still lagged behind the venerable Windows 7, which refused to budge from its dominant spot.
According to California-based analytics vendor Net Applications, Windows 10 added a full percentage point in June, accounting for 35.7% of the user share of all personal computers and 40.4% of all those running Windows last month. (The second number is larger than the first because Windows powered 87.9% of all PCs, not 100%.)
The 40.4% represented an estimated 606 million Windows personal computers, calculated using Microsoft’s oft-cited number of 1.5 billion Windows PCs