The official Android Developers website has recently released an updated metrics report on the currect distribution of the Android platform.
This means that Android 2.x versions account for over 70% of the Android distribution. If you head on over to the Android Developers website you can also view a graph of the historical distribution over time, which is quite revealing. Here, we can see that Android 1.5 held is use rate until well into May 2010. However, since the advent of Android 2.2 and its roll out onto newer devices, Android 1.5 usage has declined noticeably. Perhaps one of the contributing factors is that original contract durations are coming to a close and those early adopters are now finally grabbing the latest Android devices. Of course, it goes without saying that the general Android market share has increased, which will also account for the Android 2.x overall increase as this is the version most commonly shipped on newer devices.
[Source: Android developers]