iTunes Store US celebrates its fifth birthday today, publishing a new section to the online media service to mark the historic date.

Apple launched the iTunes Store in the US on 28 April 2003. To mark this, Apple's page takes a look back at "all of the great music, video and exclusives you first discovered on iTunes, highlighting the songs and shows that defined each year."

The company also declares it now offers a catalogue of ten million tracks in the US - 9.8 million more than the 200,000 songs offered on launch of the service five years ago.

iTunes sold 275,000 tracks in the first 18 hours of its existence, shifting one million songs within its first five days. Sales grew exponentially when iTunes for Windows shipped in October 2003, selling one million songs in three days. On 15 December, 2003 Apple announced that it had crossed 25 million songs sold. The service launched in France, Germany and the UK on 16 October, 2003.

Citing NPD data, Apple this month confirmed the iTunes Store had surpassed Wal-Mart to become the number one US music retailer in January and February 2008.

A Wired report this morning reprises observations published earlier this month in which a blogger deduced that, should Apple maintain its current 70 per cent marketshare for iTunes, its music service will account for 28 per cent of all music sold in the world by 2012.

In-Stat research claims digital music sales will account for 40 per cent of music sales by 2012.