Google's Android Developers team released the Android platform version statistics for the data collected during a 14-day period ending on March 5, 2012.
As a reminder, these are representative of the entire Android ecosystem and comprise devices that have accessed the Android Market within the last 14 days, so these would be "active" devices.
The following pie chart and table is based on the number of Android devices that have accessed Android Market within a 14-day period ending on the data collection date noted below:
Each dataset in the timeline is based on the number of Android devices that accessed Android Market within a 14-day period ending on the date indicated on the x-axis.
Here's the breakdown:
|Android 2.3 -|
|Android 2.3.3 -|
|Android 4.0 -|
|Ice Cream Sandwich||0.4%|
[Source: Android Developers]