1% rule - Wikipedia

The 1% rule is a rule of thumb holding that only about 1% of users of an Internet community actively create new content, while the other 99% only lurk. The term was coined by Ben McConnell and Jackie Huba, and the article notes that the 90–9–1 variant describes wikis, where 90% of participants only consume content, 9% edit it, and 1% add content. A 2014 paper on four digital health social networks, by van Mierlo, concluded that the rule was consistent across the four support groups, with a handful of "Superusers" generating most content. The article adds that the actual percentages likely vary by subject.