If there's one thing that Apple can laugh in Google's face about iOS adoption rate vs. that of Android. Because it controls the entire ecosystem, it can immediately deliver updates of your operating system to many more devices.
O iOS 12 had already hit 50% adoption by mid-October, and now exceeded 70% among all iPads, iPhones, and iPods in use:
If we focus only on the devices launched in the last four years, the rate goes up a little bit:
Among you readers of The adoption of new systems is always faster. Here, iOS 12 is already in 85% of devices, iOS 11 at 9% and previous versions at 6%.
Here's the current chart from the Android world:
The most direct / fair comparison with iOS 12 would be Android 9 “Pie”, also released in 2018; but he is not even on the list probably because he still has a very small representation; Android 8 “Oreo”, 2017, is on 21.5% of devices in use. To reach 70% of iOS 12, then we have to add the percentages of Android 7 “Nougat” and Android 6 “Marshmallow”.