CD sales in the US have fallen 20 per cent, but from an extraordinary high. Liebowitz says that during the history of the vinyl LP, sales rarely exceeded two per US citizen a year. Prerecorded cassettes did better - sales peaked at about 2.5 a citizen. Sales of CDs peaked a few years back at more than five per citizen a year. Even now US citizens buy more than four CD albums each a year, roughly twice as many as they ever did in the days of the vinyl LP.

Via Rocknerd.org