Imagine a society with perfectly equal income distribution so that every person earns the same amount; 1% of the population controls 1% of the income, 10% of the population controls 10% of the income, and so on. When plotted on a graph such as the one below showing the population on the X axis and percent of the total societal income on the Y axis, a perfectly equal society produces the straight, 45 degree dotted line. However, when we look at how income is actually distributed in societies, we see that a small group of wealthy individuals often earn the majority of the total income paid in that society. If plotted, unequal distributions produce curves like the solid line on the graph. In the example graph, the poorest 80% control only 20% of the income.
In 2009, the Commonwealth had a Gini Coefficient of approximately .47. This is similar to the degree of inequality found in Mozambique, Nepal, and Rwanda.