Here are the stats:

• Age: 9 years
• Units sold: 278,545,000
• Net sales: $47,833,000,000

Note the seasonal patterns of quarterly sales in the chart, with Sonic-the-Hedgehog-style Christmas spikes. Note also the major inflection points, when sales accelerated:

• Q1 2004: iTunes for Windows
• Q4 2004: iPod mini, clickwheel, overseas expansion
• Q2 2005: iPod shuffle
• Q1 2006: iPod nano
• Q1 2007: Entire line overhauled
• Q1 2008: iPod touch

By 2006, the iPod was Apple’s (AAPL) single largest source of revenue, bigger than the Mac. Today it accounts for less than 10%, eclipsed by the iPhone, the iPad and the resurgent Mac. See Horace Dediu’s chart below (he’s got an updated version here):

Below, per request of reader RattyUK, a chart of iPod unit sales with “the other iPod device,” the iPhone, added in.

For a photo retrospective of the iPod’s first nine years, see Dan Frommer’s slide show in Silicon Alley Insider.

[Follow Philip Elmer-DeWitt on Twitter @philiped]