Remember that iOS vulnerability that Apple patched with iOS 9.3.5? Yeah, it infected almost no phones. By contrast:

It was a bad week for millions of Android phone users. Two critical vulnerabilities were disclosed but remain unpatched in a large percentage of devices, while, separately, malicious apps were downloaded as many as 2.5 million times from Google’s official Play Marketplace.

http://arstechnica.com/security/2016/09/two-critical-bugs-and-more-malicious-apps-make-for-a-bad-week-for-android/