Canada’s income earners are divided into quintiles.
The percentage of the country’s income and the quintile are arranged in a graph like such:
The graph should follow a straight line.
If it does not, then it is compared to the straight line, the area is found. This area is passed to some formula and the Gini Coefficient is computed.
If it is not apparent that Income is proportional to quintile, then Income% is cumulative regarding each population quintile. If you add them all up, you get 100%