| Año | Valor |
|---|---|
| 1960-01-01 | 32.345810 |
| 1961-01-01 | 32.458868 |
| 1962-01-01 | 32.568402 |
| 1963-01-01 | 32.671178 |
| 1964-01-01 | 32.768307 |
| 1965-01-01 | 32.858419 |
| 1966-01-01 | 32.942054 |
| 1967-01-01 | 33.016960 |
| 1968-01-01 | 33.084968 |
| 1969-01-01 | 33.146675 |
| 1970-01-01 | 33.208451 |
| 1971-01-01 | 33.270549 |
| 1972-01-01 | 33.335878 |
| 1973-01-01 | 33.399191 |
| 1974-01-01 | 33.461379 |
| 1975-01-01 | 33.522511 |
| 1976-01-01 | 33.579072 |
| 1977-01-01 | 33.115865 |
| 1978-01-01 | 32.510756 |
| 1979-01-01 | 31.936314 |
Fuente: World Bank