California stadium rockers Journey have reached an unlikely milestone in popular song: their power ballad Don't Stop Believin' has become the biggest-ever catalogue song on digital platforms.

First made available through Apple's service in April 2003, it is the first catalogue song - meaning a song released in the pre-digital era, but later re-released through the iTunes store - to exceed sales of 2m, according to statistical powerhouse SoundScan.

Part of Don't Stop Believin's resurgence in popularity can be put down to its inclusion in the finale of HBO's hit mafia drama The Sopranos in June last year.

iTunes sales rocketed 482 per cent in the period between the episode airing on June 9 and the following Tuesday, June 12.

Originally released in 1981, the track, from the band's Escape album, is described by All Music Guide as having "one of the best opening keyboard riffs in rock".

Meanwhile, Apple themselves are having a spectacularly good recession, recently announcing a 34 per cent increase in music products and services in 2008. They also reported a jump from $2.5bn last year to $3.34n for revenues from iTunes downloads, and iPod devices and accessories. However, music sales counted for just 10 per cent of all Apple sales this year.