Seems high (Score 1, Informative)

I work for a midsized ISP in Michigan and we monitor information about our bandwith usage and distribution by service/protocol with netflow. We use this information for capacity planning, verifying abuse complaints, billing, etc.

Using netflow data from our core routers, we estimate peer to peer traffic to be 1/3 of our bandwidth utilization. This is based on the assumption that most p2p applications run on their default ports. I believe this to be a fairly safe assumption since we do not police our customers or restrict them from using p2p apps. The number one thing we could do to reduce our bandwidth usage right now would be to install transparent caching services for HTTP, some 50% of our bandwidth is HTTP traffic.