Application Statistics is a new type of dashboard in the Market Developer Console that gives an overview of the installation performance of apps. It provides charts and tables that summarize each app’s active installation trend over time, as well as its distribution across key dimensions such as Android platform versions, devices, user countries, and user languages. For additional context, the dashboard also shows the comparable aggregate distribution for all app installs from Android Market (numbering in the billions). Developers could use this data to observe how their app performs relative to the rest of Market or decide what to develop next.
know more: http://android-developers.blogspot.com/2011/03/application-stats-on-android-market.html