Apple's latest version of iOS, iOS 7, is now installed on 78 percent of all iPhones, iPads, and iPods, the Cupertino, Calif., company says. The preceding version, iOS 6, is still being used by 18 percent of Apple device owners, while just 4 percent use any earlier versions, Apple said. The numbers were measured by the App Store during the seven-day period ending Sunday, CNET reported, and posted on the App Store Distribution page. The growth trend of iOS 7 is ongoing; earlier in December it adoption figure was 74 percent, and in mid-October it sat at 64 percent. A large portion of the rise in iOS 7 installations is likely due to new iOS devices that were given and received over the holidays with iOS 7 preinstalled. Not all Apple devices are capable of running iOS 7; it is incompatible with iPhones prior to the iPhone 4, iPods before the fifth-generation iPod Touch and the original iPad.