Under one percent of Android devices affected by potentially harmful applications
Based on data collected by Google, less than one percent of Android devices had a potentially harmful application installed last year. This includes devices on which users have installed applications from outside the official Google Play store.
The data was collected through a feature called Verify Apps that was first introduced in Android 4.2 back in 2012. The feature, which was also backported to Android 2.3 and higher in 2013, checks locally installed applications for potentially harmful behavior regardless of whether they were downloaded from Google Play or other sources.
Verify Apps initially scanned applications only at installation time, but since March 2014 it also performs background scans, so it can later detect malicious applications that weren’t flagged when they were initially installed.