Accumulative Line Graph

source: http://ingrimayne.com/econ/AllocatingRationing/MeasuringIncomeDist.html

Developed by economist Max Lorenz in 1905, the Lorenz Curve demonstrates the income distribution of a specific population. Economists generally use the Lorenz Curve to measure income inequality. The area between the line of perfect equality and the observed Lorenz Curve is known as the Gini coefficient; the higher the Gini coefficient, the higher the incidence of income inequality.