Gini coefficient

The Gini coefficient (also known as the Gini index or Gini ratio) is a measure of differences in income. It was developed by the Italian statistician Corrado Gini in 1912.

The Gini coefficient by countries (1989-2009)

Definition

The Gini coefficient is usually a number between 0 and 1 (or 0 to 100). 0 means a country where the income is equally distributed. On the other hand, 1 means that one person owns everything but the rest owns nothing. In reality, all scores are between 0.25 and 0.6 (between 25 and 60 on the 0 to 100 scale).

Statistics

The table below is about the world Gini coefficient (not by single countries).

Income Gini coefficient
World, 1820-2005

Year	World Gini index[1][2][3]
1820	0.43
1850	0.53
1870	0.56
1913	0.61
1929	0.62
1950	0.64
1960	0.64
1980	0.66
2002	0.71
2005	0.68

The table below shows the income Gini coefficient of the United States from 1947 to 2009.

Income Gini coefficient
United States, 1947-2009

Year	pre-tax Gini
1947	0.413
1967	0.397
1968	0.386
1970	0.394
1980	0.403
1990	0.428
2000	0.462
2005	0.469
2006	0.470
2007	0.463
2008	0.467
2009	0.468