Google at beginning of each month publishes the distribution of Android versions. This way developers can assess on version to program their applications to take advantage of the new features offered by each new version of Android and to reach the largest audience.
For the realization of the distribution is taken into account the version that is being executed on each phone, regardless of whether it has an official sign or not. If they had only considered the official firmwares certainly data would be different.
Data from this month are good. More than half of mobile phones that are in circulation as shown in the first graph using Android 2.2, followed by Android 2.1 with a 31.4%. Only 10.2% still Android 1.5 and 1.6, but this percentage can even decrease more during the coming month, since they are still updating mobile from the 1.6 to the 2.X.
The less extended version is Android 2.3 version. Just 0.8%, something that was expected, since officially only the Nexus S has it, and there are still few mobiles that you can install this version not officially.
This month is expected to be launched the first Android 3.0 tablets and finally out Android 2.3 for the Nexus One so have to see if in March continues to be Android 2.2 the most extended version.