After four months of availability, Apple's newest mobile operating system, iOS 9, is now installed on 75 percent of active iOS devices as of January 11, according to new numbers posted on Apple's App Store support page for developers.

iOS 9 adoption has climbed from 71 percent to 75 percent over the course of the past month, which is when Apple last updated iOS 9 adoption numbers. As iOS 9 adoption grows, the number of people using iOS 8 and earlier operating systems has declined. 19 percent of iOS users continue to use iOS 8, while 7 percent use an earlier version of iOS.



iOS 9 adoption has outpaced iOS 8 adoption. At four months after launch, iOS 8 was installed on 68 percent of active iOS devices. In fact, iOS 9 adoption is nearly on pace with iOS 7 adoption, which was installed on 79 percent of devices four months after it was released in 2013.

In September, when iOS 9 hit a milestone that saw it installed on more than 50 percent of active iOS devices, Apple called it the "fastest iOS adoption ever," and said it was on pace to be downloaded by more users than any other software release in Apple's history.

The latest installation growth follows the release of iOS 9.2 on December 8, which introduced a huge number of bug fixes and brought improvements to Apple Music, Mail, and iBooks. iOS 9 adoption may see another boost with the release of iOS 9.3, which is currently in beta testing.

iOS 9.3 is one of the biggest updates to iOS 9 yet, introducing a new Night Shift mode, new Quick Actions, and improvements to several apps and features like Notes, Apple News, Health, and CarPlay.