It's time for a chart rule review: as the download market booms, chart rules barring digital-only singles should be revisited.(EDITORIAL)

Nobody can dispute the impact downloads have had this year on reviving--and arguably even saving--the singles market, but until recently they largely served to boost the overall sector's size rather than having too much influence on the Top 40.

But analysis outlined in this week's issue shows that, increasingly, 50% or more of some hits' weekly singles sales are coming from digital music retailers. This is a far cry from only six months ago when, at the time of the combined chart's launch, typically 8090% of sales at the top end of the chart were still being achieved within the physical market.

Despite ever-shrinking volumes, the physical singles business remains hugely important, with both Arctic Monkeys and McFly a week ago securing top three debuts largely via the high street. But, overall, it is digital which is increasingly dictating the shape of the chart, allowing the likes of Kanye West's Gold Digger and Daniel Powter's Bad Day to recently enjoy extended Top 10 runs while lower down keeping the likes of KT Tunstall's Suddenly I See alive long after its physical impact has been extinguished.

But, despite this growing trend, digital's influence on the combined chart is being artificially held back by a rule introduced at the countdown's birth, dictating that, unless a ...