OK, here's a study that's kind of old, and doesn't apply to just modem people, but I doubt things have changed much since. I'd love for someone to repeat this analysis today.

http://www.firstmonday.dk/issues/issue5_10/adar/

"Specifically, we found that nearly 70% of Gnutella users share no files, and nearly 50% of all responses are returned by the top 1% of sharing hosts."

My experience on Napster, as of a year ago when their filters became very effective, is that the clear majority of people share either zero or less than 10 files, probably just what they've downloaded during their current session. Large numbers of other people who have files shared use a firewall to block uploaders. So, from what II've seen over the last 2 years of file sharing is that most people are freeloaders.

I admit I shared nothing when I was on 28.8 dialup because it takes 20 minutes or more to download a file even with nothing else using my bandwidth. Waiting 30+ minutes for one file (that often got cut off) while other people are using my bandwidth for uploading is unacceptable to me.

The people who bug me are the ones with broadband who download many of my files and consistently have nothing shared. I cut those leeches off in a hurry. This is P2P not a client-server network, at least for broadband users.