Is one out of every four MP3 players sold an iPod?

BusinessWeek decides to kick the tires on the widely held assumption that one out of every four MP3 players sold worldwide is an iPod, and finds that the truth is little murkier. Since there aren't any reliable sales figures outside of Japan, the US, and Western Europe, you have to look at the number of chips for digital audio players that were sold last year (15 million) and then compare that figure with the number of iPods sold (1.5 million), something which would give Apple about 10% marketshare. They're careful to note that this includes all types of MP3 players, including Flash-based and hard drive-based, but BusinessWeek doesn't say what the numbers look like if you only consider players with hard drives. We're sure that it's the percentages for that are way more impressive.