Apple の App Store からダウンロードされたアプリが 400億本 を超えたそうです。このうちの半分くらいが 2012年 にダウンロードされ、2012年12月だけでも 20億本 がダウンロードされたそうです。これには再ダウンロードやアップデートは含まれていないっていうことなので、相当な数ですね。

App Store Tops 40 Billion Downloads with Almost Half in 2012

Record-Breaking December with Over Two Billion Downloads

CUPERTINO, California―January 7, 2013―Apple® today announced that customers have downloaded over 40 billion apps*, with nearly 20 billion in 2012 alone. The App Store℠ has over 500 million active accounts and had a record-breaking December with over two billion downloads during the month. Apple’s incredible developer community has created over 775,000 apps for iPhone®, iPad® and iPod touch® users worldwide, and developers have been paid over seven billion dollars by Apple.