IT research firm Gartner estimated that worldwide Mobile app stores revenues to reach $26 billion in 2013 compared to $18 billion in 2012 and annual downloads will reach 102 billion in 2013, up from 64 billion in 2012. 91% of total downloads are Free apps and in-app purchases (IAPs) accounts for 48% of app store revenue by 2017, up from 11%in 2012.