NPD Research released some information today on America's P2P usage (read press release). Legal downloads grew considerably in 2006, but those sales are dwarfed by the volume on music acquired on P2P networks. By the end of 2006, NPD counted 47 million "digital music households" in the U.S., of which 15 million took at least one song from a P2P site (and 8% increase over 2005). iTunes users increased almost 66% to 12.6 million.

With that 8% increase in P2P users, though, came a 47% increase in the number of files acquired (5 billion versus 3.4 billion). In a New York Times article, NPD's Russ Crupnick pointed to access to hard drive space as an impetus for heavy P2P usage. "When I talk to people who are involved in a lot of peer to peer, they’re running around with external hard drives," he said.

NPD noted a slowdown in the growth of P2P traffic, which it called "remarkable given the growth in digital music users overall, the emergence of digital video, and the expanded consumer exposure to broadband."

I can imagine news of NPD's report will revive calls to legalize P2P. Last week, former EMI exec Ted Cohen had an op-ed in Billboard magazine that called for a six-month experiment that would monetize existing P2P traffic. The time is right for such an experiment, but labels have other ideas. Earlier today, EMI announced it would drop DRM from its downloads -- showing that is is far easier to simply charge more for DRM-free downloads (and continue to prosecute illegal file sharing) than it is to negotiate the kind of revenue-sharing agreement that would enable legal P2P. Consumers get interoperability, but EMI get to stick to their preferred (more centralized) methods of distribution.