According to Apple’s developer website, approximately 72 percent of devices are now running iOS 8 as of February 2, 2015. While this number is up dramatically from estimates made in late September, it’s still lower than the 80 percent adoption rate of iOS 7 reported around this time last year.
These latest statistics report that the majority of the remaining devices are still running iOS 7, and approximately 3 percent of iOS devices operate on some prior version. As not all devices are upgradeable to the latest iOS versions, this also includes users who may be unable to upgrade without purchasing a newer device.
It’s also worth noting that these numbers are intended for developers and only include devices that actively connect to the App Store, suggesting that they may not be generalizable to the entire iOS user base.