Just when everyone else is cutting CD floor space at retail, Apple’s (NSDQ: AAPL) digital media store edged out BestBuy and Target to become the second-largest U.S. music retailer, behind Wal-Mart (NYSE: WMT), according to NPD data, reported by AP. This is by unit volume data, meaning the number of times people shop at a retailer…tough to compare digital piecemeal sales with physical packaged sales, but it makes a better headline. The comparison is based on a 12-track CD equivalency for song downloads.

Also, only about 10 percent of music acquired in the U.S. was through legal downloads in 2007, and the number of legal consumers grew by 5 million to 29 million in 2007, NPD said. An estimated 1 million consumers did not buy CDs in 2007, and 48 percent of U.S. teenagers didn’t buy any CDs during the year, up from 38 percent in the year before. The amount of music consumers bought in the U.S. rose 6 percent in 2007, though the decline in CD sales and increase in legal digital download sales still led to a 10 percent overall decrease in music spending.