https://arstechnica.com/gadgets/2018/10/half-of-enterprise-machines-run-windows-10-as-windows-7s-end-of-life-looms/

On Microsoft's earnings call for the first quarter of its 2019 financial year, CEO Satya Nadella said that "more than half of the commercial device installed base is on Windows 10."

A Microsoft spokesperson "clarified" this to say, "based on Microsoft's data, we can see that there are now more devices in the enterprise running Windows 10 than any other previous version of Windows." That description offers a little more wriggle room; Windows 10 might only have a plurality share of enterprise systems rather than the majority share Nadella claimed. But either way, a substantial number of machines in the enterprise are currently running Windows 10.