long lived phones
Numbers may be down as the market is saturated, a lot of iPhone users now are not huge apple fans and don't align themselves with the latest products, we just want a phone that works and is supported with patches and software updates for the life of the phone.
I don't have a bleeding edge iPhone having moved across to an iPhone 7 last year but I do intend to keep it for 4 years. The next phone upgrade will be when my wife replaces her iPhone 6 in a years time, she will have had it for 4 by then.
I've done Android and am heartily sick of the lack of updates, I did root a phone and installed a custom rom so I could keep a maintained OS but that meant several apps I wanted to use would not work. I seemed to have to fix issues with google services every few months. I even resorted to windows mobile for 18 months with a nice lumia handset. The key issue there were lack of apps and difficulties getting it repaired after a broken screen.. I ended up having to get it repaired via my insurance company and it came back with the wrong build on it and of course I had to resolve that. In the end having watched the rest of the family just use their phones rather than spending time regularly rebuilding them I just gave up and moved to an iphone.