Chances are the apps you're using are free, at least according to Gartner. According to research, 90% of apps 95.6 billion apps downloaded this year will be free. Furthermore, by 2016 Gartner expects that 93% of an estimate 309 billion downloaded apps will be fee.
With this in mind, would-be app developers will likely have to explore other monetization models, like in-app purchases and upgrades.
(www.gartner.com)