Google represents an average 6.4% of all Internet traffic around the world

"Google now represents an average 6.4% of all Internet traffic around the world. This number grows even larger (to as much as 8-12%) if I include estimates of traffic offloaded by the increasingly common Google Global Cache (GGC) deployments and error in our data due to the extremely high degree of Google edge peering with consumer networks. Keep in mind that these numbers represent increased market share — Google is growing considerably faster than overall Internet volumes which are already increasing 40-45% each year. More data on general Internet growth trends is available in some of our earlier papers and blog posts.
While its not news that Google is Big, what is amazing is how much bigger Google continues to get.
A quick analysis of the data also shows Google now has direct peering (i.e. not transit) with more than 70% of all providers around the world (an increase of 5-10% from last year). In fact, the only remaining major group of ISPs without direct Google peering are several of the tier1s and national PTTs — many of whom will not settlement-free peer with Google due to regulatory prohibitions or commercial strategy."
Source:  Arbor Networks, 25th October 2010