Tech Researchers Calculate Digital Info - New York Times

Yow 

Add it all up and IDC determined that the world generated 161 billion gigabytes -- 161 exabytes -- of digital information last year.

That's like 12 stacks of books that each reach from the Earth to the sun. Or you might think of it as 3 million times the information in all the books ever written, according to IDC. You'd need more than 2 billion of the most capacious iPods on the market to get 161 exabytes.

Source: Tech Researchers Calculate Digital Info - New York Times