80/20 Rule

In anything, in any field their a few vital people or components the are the most productive. Those few generate most of the good or beneficial. The remainder generate little. This is usually expressed in an 80/20 ratio made popular by Joseph Juran in the 1940's. He called it the Pareto's Principle after Vilfredo Pareto an Italian economist. Eighty percent of something is responsible for twenty percent of the results and twenty percent of something is responsible for eighty percent of the results.

Examples
Why We Cheat