Apple has updated its developer website for the iOS App Store, which shows some great adoption rates for iOS 7. Apple's latest mobile OS is on 74% of devices, which is a 10% increase over October's numbers.
22% of active App Store users are running iOS 6, which means that if we combined the numbers, we're looking at 96% of iOS users being on the latest two operating systems from Apple. This is something that Apple excels in - iOS adoption rates. Compared to Android, where there are still 25.8% of its users on versions of Google's mobile OS older than Android 4.x.