Apple has just handed us a graphic reminder of the value of a closed ecosystem vs open.
iOS 8 had been released just over 4 months ago, and while that adoption rate lags behind the rate noted for iOS 7 it nevertheless is a far higher rate than what Google is reporting for Android 5.0 Lollipop.
It's been some 3 months since Google officially launched the latest version of its OS, and so far it is only running on 1.6% of the devices which visited Google Play over the past week. That is far smaller than the share for Jelly Bean (44.5%) or KitKat (39.7%).
Android has always lagged in terms of adoption so this should in no way surprise anyone. It's simply one of the downsides of having an ecosystem with dozens of suppliers, all competing with each other to release new devices.
Few of those companies can afford to keep up with the latest version of Android; they're too busy building the next model. And to be fair, the only reason Apple can afford to release a universal version of its mobile OS is that it charges a lot (they can do that without any real competitors).
As with any system, there are tradeoffs. Do you want high prices and a high expectation of quality or low prices and middling quality?
Me, I'm happier with the less constrained, hit-or-miss world of Android than I am with the locked down, costly, Apple ecosystem.