Apple formally announced iOS 9 last September, and began rolling it out a week later to several generations of its iPhones and iPads, along with the fifth-gen iPod touch. Within just three days, the update had made its way to a staggering 50% of iOS devices, making it the operating system's fastest rollout ever.
At the time, Apple's Phil Schiller said that it was "on pace to be downloaded by more users than any other software release in Apple's history" - and it's clearly continuing to make good progress on that front.
As TNW spotted, an update to Apple's Developer site reveals that iOS 9 is now installed on around 75% of devices, just four months after its launch. To put that figure into context, it took a full year for iOS 8 to reach 87% of devices.
iOS 8 is still installed on 19% of devices, with 7% using earlier versions of the OS.
In comparison, Android 6.0 Marshmallow - the latest version of Google's OS, which was officially announced three weeks after iOS 9, and began rolling out in early October - is currently installed on just 0.7% of active devices.