That's a jump from 68 percent a month ago. It's a solid chunk of devices, but considering that Apple sold 74.5 million iPhones over the holidays--all of which run the latest OS--the slow adoption rate is still surprising. One culprit: The size of iOS 8, which prevented a slew of 16GB iPhone owners from upgrading in the early days after launch. Apple is even facing a lawsuit over the size of iOS 8, with two plaintiffs complaining that 16GB iPhones and iPads don't actually have that much available storage.
Last week, iOS 8.1.3 rolled out, and one of its primary fixes is reducing the amount of storage required to perform a software update over the air. I doubt the news sent iOS 7 holdouts scrambling to install iOS 8, but I expect adoption to continue its steady advance as more and more iPhone owners realize they don't have to delete apps and photos en masse (or simply update via iTunes) to finally make the jump. Or maybe people are just happy with the performance of iOS 7--which isn't exactly a bad thing.