Cisco predicts:
Global IP traffic grew 45 percent during 2009 to reach an annual run rate of 176 exabytes per year or 15 exabytes per month. In 2014, global IP traffic will reach 767 exabytes per year or 64 exabytes per month.
I think this is way too modest, since last year (2010) already reached 245 exabytes (according to Intel).