Case study: hitting the Billboard charts by free online streaming of the album

I notice that Imogen Heap is continuing with the free streaming of her album Ellipse . And no doubt significantly because of the free streaming, Ellipse is charting at #5 on Billboard. It is a glorious album, though I think we can pretty definitely count the free streaming of the album on the web as a very effective strategy. Perhaps it will become commonplace to stream music for free in order to maximize sales.
I’d be keen to know the proportion of sales of this album and the songs on it online versus through CD. It would almost be surprising if she sold much in CDs at all, because her presence is so online..
I notice Imogen on Twitter now has over a million followers.
A bit tangentially, I just found this beautiful video of a beautiful song by Kate Havnevik, who I found through collaborative filtering and Imogen’s music. If you like Imogen you’ll absolutely like the extraordinary Kate. (note that it doesn’t start for 10 seconds)