| Año | Valor |
|---|---|
| 1970-01-01 | 16.596800 |
| 1971-01-01 | 16.610700 |
| 1972-01-01 | 20.196800 |
| 1973-01-01 | 21.880500 |
| 1974-01-01 | 21.087000 |
| 1975-01-01 | 18.865100 |
| 1976-01-01 | 19.115800 |
| 1977-01-01 | 16.485700 |
| 1978-01-01 | 15.604400 |
| 1979-01-01 | 13.410900 |
| 1980-01-01 | 12.147800 |
| 1981-01-01 | 10.013000 |
| 1982-01-01 | 10.900500 |
| 1983-01-01 | 10.001600 |
| 1984-01-01 | 9.552900 |
| 1985-01-01 | 9.113000 |
| 1986-01-01 | 8.243500 |
| 1987-01-01 | 8.686400 |
| 1988-01-01 | 8.706400 |
| 1989-01-01 | 9.164000 |
Fuente: World Bank