MP3 players reaching critical mass?

From where I sit, it's hard to believe that anywhere less than 50 percent of Americans own an MP3 player. Of course, I live in a major Bay Area city that's rife with public transportation--something I inherently connect with portable audio devices. It also happens (or happened) to be the center of the technological universe... well, in the States, anyway. Oh yeah, and I cover MP3 players at a tech-oriented media company. Perhaps my viewpoint is slightly skewed. Indeed, my skew is more than slight. shows that "one in five Americans ages 12 and older owns a portable digital music player," and that number was just one in 10 a couple of years ago. (Listen to the Future Tense RealAudio file.) One in five!?! Come on people, let's get out there and buy some MP3 players!
Warning: Shameless self-promotion just employed.