1.5m people paid for music subscription services in the US in 2010

"Music subscription services had 1.5 million paying users in the US last year, up from 1.2 million in 2009. That’s according to new figures from the RIAA, which says revenues for these services still fell from $213 million in 2009 to $201 million in 2010. The RIAA’s report also reveals the continuing decline in mobile music sales, which fell from 306 million units in 2009 to 221 million in 2010, with ringtones down 41%, ringback tones down 26% and even full-track music downloads down 23%. 1.16 billion download singles were sold in the US in 2010 – up 2.1% year-on-year – for a value of $1.37 billion, up 12% as higher prices on iTunes took effect."

Source:  Data from the RIAA, reported by MusicAlly, 3rd May 2011
Full stats from the RIAA here