Cultural Note: The UK has one cable provider - Virgin Media, which also provides TV. The other major company is Sky, which is a tv company providing broadband Internet. Many UK tv channels are now available as Video on Demand; some of the "catch up" features (eg, BBC iPlayer, 4OD) are free.
This 17 GB average includes TV.
It would have been more interesting to see that number split out into different types of data.