https://techcrunch.com/2017/11/08/most-ios-devices-now-run-ios-11/

Apple has updated its App Store support page with new metrics. As of November 6, 2017, iOS 11 is now installed on 52 percent of iPhones and iPads currently in use. 38 percent of devices still run iOS 10, and only 10 percent of people are using an earlier version of iOS.

Apple usually updates this page quite quickly after the release of a major iOS update. This year, the company waited a bit as the iPhone X was released just last week, creating a new influx of iOS 11 users.