“I think that at the moment, just for streaming, iPlayer uses about 60Gbps of bandwidth (that’s about 7.5GB downloaded every second) in an evening peak. I think about 15Gbps for downloads, and about 1.5Gbps for iPhone. So overall on a particular peak day we may hit 100Gbps (about 12.5 gigabytes per second) although typically it’ll be somewhat less than that. That turns out to be up to 7PB of data transfer a month.
via CNET.