“A measure that captures prosperity should account for both the level of welfare and level of inequality. A measure that captures inequality, such as the Gini index, is an example of a measure of inclusivity. The World Bank reports the number of economies with high levels of inequality, defined as those with a Gini index greater than 40. Based on this, the number of economies with high inequality has declined by more than a third in the past three decades.”

From World Bank.