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 (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 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).
The Gini coefficient can be shown using the Lorenz curve. It shows how income is shared across a population, from the poorest people to the richest. The Gini coefficient is based on the area between the Lorenz curve and the line of perfect equality. A larger area means a higher Gini coefficient.
The table below is about the world Gini coefficient (not by single countries).
| Year | World Gini index |
|---|---|
| 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.
| 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 |