Analytics firm Distimo indicates that in-app purchases now account for 72 percent of revenue generated by the App Store. A sample of the top 300 apps in each category showed that the number of free apps has grown by 34 percent since 2010, with paid apps increasing by 7 percent.

Only 4 percent of apps allow in-app purchases, however their revenue has increased 28 percent from the same point last year. 48 percent of that revenue comes from free apps, with 24 percent coming from paid apps that allow in-app purchasing.