Green Day's new album, 21st Century Breakdown, has debuted at Number One on the British album charts.The long awaited follow-up to their mega-selling 2004 album, American Idiot, topped the charts despite only being on sale for two days. 21st Century Breakdown fought off tough competition from indie mob Maximo Park who entered the UK Top 40 at Number Six and Blur man Graham Coxon who is at 36.In related news, Biffy Clyro side-project, Marmaduke Duke, debuted at number 14 with their second album, Duke Pandemonium.