However, a more intriguing issue is what makes up that extra usage. Markets like Hong Kong and Korea have very fast broadband, and high per-line traffic. When you ask insiders in those markets what all that traffic is, they often look a bit shifty and then whisper 'piracy'. Until today I hadn't seen any hard data to back up this assertion.
However, I've just come across a report from COMBO, an EU funded project looking at fixed-mobile convergence. (It has blue-chip participants - France Telecom, Deutsche Telekom, Telefonica, Alcatel Lucent, Ericsson and several others). On page 104 of the report is the following data for traffic of FTTH and ADSL customers of France Telecom in October 2013 :
Upstream and downstream traffic combined.
As you can see, FTTH users have roughly double the usage of ADSL customers. However, 58% of the additional traffic is down to P2P. Peer-to-peer is a protocol with legitimate uses, but it's very largely used for piracy. It's what enables Bittorrent for example (and is beloved of the copyright-sceptics of The Pirate Bay).
FTTH customers have 4.2x the P2P traffic of ADSL customers, mostly because they upload 7.5x more than ADSL customers. Indeed, for every pirate-byte they download, FTTH users are uploading 2.6. In the words of the report, "this allows us to conclude that some FTTH customers are becoming P2P servers".
Superfast advocates claim significant externalities (societal and economic impacts) for faster broadband. But externalities can be negative as well as positive. See the rigging on the rather fine pirate ship above? Fibre-optic cable, every strand.