It’s funny, because for a moment there I thought you said ‘download cannibalization‘…
And these are just the paid ones. According to IFPI stats, paid downloads traditionally represent about 1/20th of broader downloads (the rest being illegally obtained). Which means there at least half-a-trillion downloads waiting for or entering a cloud-enabled reincarnation – on iTunes Match, Amazon Cloud Drive, or Google Play.
The dataset is here.
Written while listening to Fedde Le Grand.