via Ponto Media:

«The chart landmark comes less than a year after download sales were first counted towards the top 40. Before that, the singles scene looked rather gloomy - sales had dropped from 80 million in the late 1990s to little more than 20 million in 2005. But then came the legal download services, led by Apple's iTunes, which launched in the UK in June 2004. (...) So instead of going to a record shop to hand over £2-4 for their favourite song, fans could instead pay 79p from the comfort of their own homes. (...)More than 26 million songs were downloaded legally in the UK in 2005 - up from virtually zero two years earlier. And downloads now account for about three quarters of all singles sold. (...) A recent rule change means digital sales start counting towards the chart the week before the CD release. But Gnarls Barkley's song was first made available to download on 13 March, meaning there were two extra weeks when thousands of fans were legitimately buying the song - but it was not appearing in the chart».