Back in December 2017, it was revealed that the percentage of iOS devices running on iOS 11 was at 59%. However it seems that the number has since increased in the month of January, at least according to Apple’s Developer Support page in which they have revealed that iOS 11 is now installed on 65% of all compatible devices.
iOS 11 is currently supported on devices as old as the iPhone 5s which was released back in 2013, making it a phone that’s a little over four years ago. This is one of the distinct advantages of the iOS platform and iOS devices, where Apple typically offers support for relatively long periods of time.
This is versus Android in which how long a device is supported for ranges from manufacturer to manufacturer, and sometimes only the flagships are updated with lower-end devices usually being left behind. Of course there are other valid reasons why one might choose iOS over Android and vice versa, but timely updates is an advantage of iOS that’s hard to ignore (unless you own a Google Pixel device).
That being said despite being installed on more than half of iOS devices, iOS 11 is considered to be lagging behind its predecessors, where iOS 10 was installed on 76% of devices in January 2017. Also given Apple’s controversy over iOS updates slowing down older iPhones, we wouldn’t be surprised if this could potentially affect the adoption rate of future iOS releases.