Mobile Application Stores : Downloads and Revenue

The iPhone has no doubt revolutionized the mobile phone industry and the app economy, spurred by the addition of thousands of new mobile apps everyday to the various app stores, has been booming. So, how big is it expected to grow? Gartner recently published their predictions for the near term. Here is the value of the mobile application market corresponding to the number of apps that is estimated to be downloaded

2009 : $4.23 billion (2.5 billion downloads)
2010 : $6.77 billion (4.5 billion downloads)
2013 : $29.47 billion (21.6 billion downloads)