iCloud isn't about backing things up. It's about syncing your data across devices.I'd be surprised if the stats. reflect the uptake that Apple were hoping for. I may be proved wrong, but I believe the majority of IOS device users prefer to keep their media libraries and files on their machines. Personally, I do not use the cloud to back anything up. With a TC, and NAS I have ample disaster prevention in place.
Ii would, however be interesting to see them. As posted here, Apple tend to trot such stuff out in keynotes, so we may know soon.