A new Forrester Research report Social Technographics breaks down the activity of social computing into 6 areas of activity. Authors of the report, analysts Charlene Li and Josh Bernoff, use the term Social Technographics to describe a population according to its participation iat various levels.

Joe McKendrick of Fast Forward blog has a summary of the reports findings here

“Creators” (13%): Publish Web pages, publish blogs, upload video to sites like You Tube
“Critics” (19%): Comment on blogs, posting ratings and reviews.
“Collectors” (15%): Use RSS, tag Web pages
“Joiners” (19%): Use social networking sites
“Spectators” (23%): Read blogs, watch peer-generated video, listen to podcasts
“Inactives” (52%): Yeah, the rest of the world.

The figure I found interesting was that 13 percent of people actually make something. Sounds like a similar percentage to real life – but I have no figures to compare - it is more a hunch than anything else.