(3) What activities make up the (web-based) social pyramid? - Quora
Notice that the numbers don't add up to 100%. That is because someone can be one of several roles. In fact s Spectator is likely to be a Joiner and a Creator.
The key point to take away from this is that the 20/80 rule essentially holds up. 80% of the population is reading, collecting content, commenting on content or stating their opinion on content which is created by about 24% of the total population.
When ever planning a collaboration system remember that only 20% of your users will ever engage in Creation behavior, and most them them at a very low level. If you have a small department of say 30 people there is a chance that you will not have enough people willing to produce content with enough time to produce content.