Based on current download rates, the crossover could come before the end of the year
The chart at right, drawn by Asymco's Horace Dediu, compares two of Apple's (aapl) signal developments: the growth of legal digital music downloads and the growth of downloadable mobile apps.
Graphed on top of each other, by months since launch, the chart shows traffic on the App Store reaching in 2.2 years the same total -- nearly 7 billion downloads -- that the iTunes Music Store reached in five.
"The two curves," Dediu writes, "are likely to be the same height (around 13 billion each) before the year is over."
Commenting on Dediu's post, AppsFire's Ouriel Ohayon says we shouldn't be surprised, even though there are 12 million songs on iTunes and only about a quarter million apps. "Apps are the new ringtones and wallpapers," he writes, "the new way (and the best way)" to personalize your phone." Moveover, he adds, many of them are free.
He focuses on a second Dediu chart, copied below, that shows that the two download rates are not nearly as smooth as the first suggests. In fact, this fever chart shows a sharp falloff in daily download rate for songs starting about a year ago. Ohayon doesn't offer an explanation. Any theories?
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[Follow Philip Elmer-DeWitt on Twitter @philiped]