Nearly five years after Apple launched the first appstore, the worldwide revenue for apps is expected to grow with 62% to 25 billion dollars this year. Both the Apple appstore and Google Play now offer more than 700,000 apps each. In early 2010, the Apple appstore offered around 140,000 apps. The Wall Street journal has a nice background article about apps in which it quotes from a Gartner research and some other sources.
Apple and Google Play are in a neck-in-neck race nowadays in terms of smartphone app catalog size and usage. But Apple still clearly dominates in revenue. Analysts estimate that the revenue in Apple's store is 3 times bigger than in Google Play.
The article also has some interesting usage data. Consumers spend an average of two hours a day on apps. The average usage time has doubled in the last two years. But there is also a fierce competition among apps. About 63% of the apps used daily now differ from those used daily a year ago. Moreover, consumers focus on a handful (8) apps at time.