The number of mobile apps downloaded around the world increased by 104% in 2012 to 60.1bn, according to new figures from Berg Insight.
Those 60bn apps generated an estimated €6.4bn in revenues, including direct revenues and in-app ad revenues.
Direct revenues, including paid applications, in-app purchases and subscription services, accounted for 80% of the total at €5.1bn.
But this proportion is set to fall as in-app advertising develops. By 2017, Berg forecasts that this sector will account for 25% of all app revenues and be worth £3.5bn.