The latest AdDuplex report shows that 26 percent of Windows 10 PCs are on the latest version, 21H1. And that 0.9 percent are already on Windows 11.
“More than 26 percent of PCs run the 21H1 update of Windows  and 0.9 percent are already on Windows 11,” the report explains, noting that the data is based on a survey of about 60,000 Windows 10 and 11 PCs. “[The] 2020-21 versions of Windows 10 are now on more than 88 percent of Windows 10 PCs surveyed.”
I can’t find AdDuplex reports for May or June, so the last comparable month is April, when Windows 10 version 20H2 hit 40 percent usage share. Since then, things have shifted a bit with the release of Windows 10 version 21H1 and the first Windows 11 previews.
This month, Windows 10 version 20H2 is still the most-used version, but its share has fallen to 36.3 percent. Version 21H1 is in second place. And version 2004 brings up the rear with 24.6 percent usage.
And that 88 percent figure? Unchanged since April. Interesting.