Chart of the day: The rise and fall of Apple’s iPod by Philip Elmer-DeWitt @FortuneMagazine April 15, 2013, 10:51 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons Data: Apple, Piper Jaffray. Chart: PED. The spikes represent holiday sales. FORTUNE — It’s easy to forget that only six years ago the iPod was Apple’s AAPL biggest money maker, generating (in Q1 2007) more than 48% of the company’s revenue. Now the iPod is almost an afterthought in quarterly reports dominated by the iPhone, iPad and Mac — second-to-last among Apple’s six revenue streams, below iTunes and above Accessories. The last entry in the chart above was drawn using the median estimate of iPod unit sales (6.2 million) submitted by 54 Apple analysts — 31 Wall Street professionals and 23 amateurs. They all expect the trend that began with the launch of the iPhone and the iPod touch to continue: More and more of the original iPod’s core business absorbed by iOS devices. It’s a classic case of product disruption, except in this case a company disrupted its own cash cow. According to disruption theory, what Apple’s engineers should be doing now is inventing the product that will absorb the iPhone. Below: The individual iPod unit sales estimates submitted so far by our panel of analysts. In this instance, the pros (with an average estimate of 6.22 million) are slightly more bullish than the amateurs (6.15 million). We’ll find out who was closest to the mark when Apple reports its fiscal Q2 2013 earnings on April 23. Pros in blue, amateurs in green. Chart: PED. Thanks once again to Posts at Eventide‘s Robert Paul Leitao for pulling together the Braeburn Group numbers.