[johngunderman]

While I don't have any statistics, I do not doubt their claim. CloudFlare is a CDN, and as such will handle an enormous amount of traffic. As an example of this, Akamai, a large CDN, handles approximately 20% of the total traffic on the internet. In fact, many sites, such as Wikipedia, Twitter, even Amazon and Google, actually host static content through Akamai. All this content adds up to significant amounts of traffic.

EDIT: Link -- http://www.akamai.com/html/technology/dataviz3.html