| Año | Valor |
|---|---|
| 1960-01-01 | 17.796935 |
| 1961-01-01 | 18.103617 |
| 1962-01-01 | 18.415562 |
| 1963-01-01 | 18.730853 |
| 1964-01-01 | 19.050976 |
| 1965-01-01 | 19.373273 |
| 1966-01-01 | 19.700158 |
| 1967-01-01 | 20.029716 |
| 1968-01-01 | 20.363395 |
| 1969-01-01 | 20.700534 |
| 1970-01-01 | 21.046948 |
| 1971-01-01 | 21.401934 |
| 1972-01-01 | 21.768502 |
| 1973-01-01 | 22.142357 |
| 1974-01-01 | 22.525667 |
| 1975-01-01 | 22.919184 |
| 1976-01-01 | 23.320003 |
| 1977-01-01 | 23.719755 |
| 1978-01-01 | 24.133890 |
| 1979-01-01 | 24.566136 |
Fuente: World Bank