After iOS 12 release, now installed on 83% of devices released in the last four years, as confirmed by Apple on the App Store support page for developers.
Since the launch of iOS 12, Apple has started to show the operating system’s diffusion data taking into account the oldest devices, and including only those released in the last four years. Hence the difference between the two percentages.
Considering all the devices, iOS 12 is installed on 80% of the iPhone, iPad and iPod touch in circulation, iOS 11 on 12% and previous versions on 8%. If, however, only the devices released in the last 4 years are taken into account, the percentage of iOS 12 diffusion rises to 83%, while that of the versions prior to iOS 11 drops to 5%.
At the beginning of January, iOS 12 was installed on 78% of devices, confirming that this version spread faster than iOS 11 which, in April 2018, was installed on 76% of devices.