Apple's iOS 10 is now used more than any other version of the operating system. More than half of iOS devices have already upgraded to the latest software, according to new numbers from Apple. SEE ALSO: 12 hidden features in iOS 10 The update is now installed on 54% of devices, according to stats posted on Apple's developer site. Last year's iOS 9 accounts for 38% of devices while just 8% of devices are running iOS 8 or earlier.