The 36% Rule and the Inevitable Ascendance of the iPod and of Online Music Distribution

I’ve come across a graph in Swivel that seems to illustrate the descriptive power of the 36% rule and why online is now a de-facto channel for music distribution.

In my post about Dr. Rodrigues’ 1/e (or 36%) rule you’ll remember that the rule was verified against the rate of adoption of hybrid corn across the states last century. This very same phenomenon is now illustrated by the few plots shown in the link above. Notice how one distribution medium’s decline intersects the other’s ascendance at around 36% from the maximum. What I find interesting is that the intersection points occur at about 36% from the maximum and not that the new channel starts once the previous reaches 36% of the maximum, it also seems that iPod sales have dropped more than 36% from their maximum and a new channel has not yet been identified.. could that be illegal (and thus non-trackable) music exchanges in p2p networks?