I still have a copy of Jakob Nielsen's 'Web Usability' from 2000 - it's as good now as it was then and the research his company does is, I believe, recognised for that it tells us.
Only a tiny fraction of people contribute to content creation online, a few more comment while the majority, over 90%, are reader/observers. (I loathe the pejorative term 'lurker' - there is nothing wrong with reading passively, or watching passively or listening passively. Thankfully not everyone feels the desire to write, to direct or to compose music.
1-9-90 is the split for all online content
0.1% - 5% - 94.9% is the split for blogging - those who blog, comment on blogs or simply read them.
And so he gives splits in Wikipedia and in Facebook.
You'd think a community of postgraduate students doing an entirely online course might be closer to 25 - 50 - 25. Why not the other way around? 90-9-1%
What a noisy world it would be if we all felt the urge to stand on a soapbox at the end of the street and prattle on, or busk all day in the Shopping Precinct.
I'm unconvinced of these stats though. Defining a 'blog' is like pointing at a passing cloud and saying 'that one's mine'.
Where are the stats to be found on such things?
And that person who did those cave paintings 35,000 years ago. I bet he was a 1% er. So what does that say for the other 99%? Nothing at all. They may never have even seen them.
Nielsen. J. (2006) Participation Inequality: Encouraging More Users to Contribute. (Accessed 16 February 2013 http://www.nngroup.com/articles/participation-inequality/ )