Wikipedia

In Internet culture, the 1% rule is a general rule of thumb pertaining to participation in an Internet community, stating that only 1% of the users of a website actively create new content, while the other 99% of the participants only lurk. Variants include the 1–9–90 rule (sometimes 90–9–1 principle or the 89:10:1 ratio),[1] which states that in a collaborative website such as a wiki, 90% of the participants of a community only consume content, 9% of the participants change or update content, and 1% of the participants add content.

Similar rules are known in information science; for instance, the 80/20 rule known as the Pareto principle states that 20 percent of a group will produce 80 percent of the activity, regardless of how the activity is defined.