A prediction that the US will see a record year for digital music sales may not justify a street party – if digital sales shrank year-on-year, the music industry would really have something to worry about. Even so, Nielsen has put a couple of numbers on 2012′s growth, saying that US digital album sales through August are up 15% on the same period last year, while Americans have already bought 1bn digital tracks this year. That means the US is firmly on course to beat 2011′s record of 1.3bn digital track sales. Nielsen points to continued growth of tablets and smartphones as a driver for downloads growth – although they’re also boosting on-demand streaming and personal radio usage.