TeleGeography reports that ".. demand for international bandwidth grew 39 percent to 138 Tbps in 2013, a 4.5-fold increase from the 30 Tbps of bandwidth used globally in 2009.Internet backbones remain the primary users of international bandwidth, accounting for 75 percent of demand in 2013. However, the drivers of international bandwidth demand are changing.
As private network operators, including large content providers like Google, Microsoft, and Facebook, expand their internal networks, their bandwidth requirements increasingly exceed those of the largest carriers .. Global network expansion has undergone a long-term shift in focus, from connecting users to users, to linking users to data centers and—increasingly—data centers to each other".
See "New global network builders emerge" - here.