Accumulative line graph or Lorenz curve

Here is an example of a Lorenz curve. Lorenz curves are often used to represent income distribution. The solid line is the Lorenz curve, which represents the actual distribution. Every point represents a statement, and every Lorenz curve has a Gini coefficient showing a line of perfect equality.
Image found at: http://img.sparknotes.com/figures/D/df794916738a067d0a15bbaeabcb81e3/lorenz.gif