| Año | Valor |
|---|---|
| 1970-01-01 | 27.011100 |
| 1971-01-01 | 28.036200 |
| 1972-01-01 | 32.660800 |
| 1973-01-01 | 34.215500 |
| 1974-01-01 | 34.044900 |
| 1975-01-01 | 32.831300 |
| 1976-01-01 | 34.187600 |
| 1977-01-01 | 31.906900 |
| 1978-01-01 | 33.019300 |
| 1979-01-01 | 30.956300 |
| 1980-01-01 | 30.314400 |
| 1981-01-01 | 28.101200 |
| 1982-01-01 | 29.381200 |
| 1983-01-01 | 30.241500 |
| 1984-01-01 | 28.677900 |
| 1985-01-01 | 28.905800 |
| 1986-01-01 | 26.537500 |
| 1987-01-01 | 27.639500 |
| 1988-01-01 | 28.378700 |
| 1989-01-01 | 29.996500 |
Fuente: World Bank