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,

TeleGeography reports that "According to new data .. Skype’s international traffic volume continues to soar ..  Skype’s on-net (Skype to Skype) international traffic grew 36 percent in 2013, to 214 billion minutes .. While the volume of international telephone traffic remains far larger than international Skype traffic, Skype’s minutes are growing much more rapidly. Skype added approximately