Apple’s iTunes Store accounted for more than a quarter of all music sales in the U.S. during 2009, according to a Billboard report. The report states that iTunes grew its share of U.S. sales to 26.7%, up from 21.4% in 2008 and more than double the 12.7% share it held in 2007. Second-place Walmart, meanwhile, saw its share shrink to 12.5% in 2009 from 15% in the prior year, something the report attributes to the retail chain’s scaling back…
