The majority of music sold in the U.S. is still via CD -- 65% market share, almost a two-to-one lead over digital, according to research firm NPD Group.

But digital sales continue to take share, now 35% of all music sales in the first half of 2009, up from 30% of sales last year and 20% in 2007.

From NPD's release: According to NPD MusicWatch, when it comes to the unit-sales volume of music sold at retail – including paid digital music downloads and CDs – Apple iTunes leads in the U.S. with 25 percent of music units sold, which is up from 21 percent in 2008 and 14 percent in 2007. Walmart (including Walmart, Walmart.com, Walmart Music Downloads) remains in second position with 14 percent of music volume sold at their stores and Web sites with Best Buy ranked third.

iTunes also continued to solidify its lead in the digital music arena, as consumer downloads from iTunes comprised 69 percent of the digital music market in the first half of 2009, followed by AmazonMP3 at 8 percent. Walmart leads all sellers of CDs with a 20 percent share of the physical music market, followed by Best Buy at 16 percent and Target and Amazon tied at 10 percent each.