So, what's the biggest catalogue download?

Here's a pop quiz question for you. Which band's song is the first catalogue track to sell more than 2 million units on iTunes? Any guesses? I suspect you wouldn't guess American rockers Journey. But their track 'Don't Stop Believin' is the biggest selling catalogue track on the market leader download store, helped, presumably, in no small part by its appearance on the finale of 'The Sopranos' last year. It's the power of the sync again. The song was originally released in 1981 and has been available via iTunes since 2003.