| Año | Valor |
|---|---|
| 1970-01-01 | 22.396900 |
| 1971-01-01 | 22.606500 |
| 1972-01-01 | 26.418700 |
| 1973-01-01 | 28.237400 |
| 1974-01-01 | 28.109400 |
| 1975-01-01 | 26.240700 |
| 1976-01-01 | 26.899100 |
| 1977-01-01 | 24.711500 |
| 1978-01-01 | 24.906500 |
| 1979-01-01 | 23.331200 |
| 1980-01-01 | 22.635600 |
| 1981-01-01 | 20.160700 |
| 1982-01-01 | 21.043500 |
| 1983-01-01 | 21.498900 |
| 1984-01-01 | 20.536300 |
| 1985-01-01 | 20.727800 |
| 1986-01-01 | 18.794400 |
| 1987-01-01 | 19.607700 |
| 1988-01-01 | 19.932700 |
| 1989-01-01 | 20.539100 |
Fuente: World Bank