Over $10 Billion was spent in Apple's App Store in 2013

"Apple today announced that customers spent over $10 billion on the App Store in 2013, including over $1 billion in December alone. App Store customers downloaded almost three billion apps in December making it the most successful month in App Store history. Apple’s incredible developers have now earned $15 billion on the App Store.
“We’d like to thank our customers for making 2013 the best year ever for the App Store,” said Eddy Cue, Apple’s senior vice president of Internet Software and Services. “The lineup of apps for the holiday season was astonishing and we look forward to seeing what developers create in 2014.”"

Source:  Press release from Apple, 7th January 2014