A quick googeling only showed data for iOS 10 but I would belive that the ballbark is the same. https://www.zdnet.com/article/ios-10-adoption-nears-15-after-fir

A quick googeling only showed data for iOS 10 but I would belive that the ballbark is the same. https://www.zdnet.com/article/ios-10-adoption-nears-15-after-first-day-of-availability/ https://www.zdnet.com/article/ios-10-adoption-nears-15-after... So 15% on the first day, with 1.5 billion active iOS devices. Thats a pretty high number of potential unsattisfied user experience.