| Año | Valor |
|---|---|
| 1981-01-01 | 29.970000 |
| 1982-01-01 | 30.520000 |
| 1983-01-01 | 25.650000 |
| 1984-01-01 | 29.770000 |
| 1985-01-01 | 32.990000 |
| 1986-01-01 | 32.530000 |
| 1987-01-01 | 34.140000 |
| 1988-01-01 | 35.670000 |
| 1989-01-01 | 36.350000 |
| 1990-01-01 | 37.240000 |
| 1991-01-01 | 38.740000 |
| 1992-01-01 | 37.790000 |
| 1993-01-01 | 40.590000 |
| 1994-01-01 | 43.430000 |
| 1995-01-01 | 46.820000 |
| 1996-01-01 | 48.370000 |
| 1997-01-01 | 49.840000 |
| 1998-01-01 | 51.750000 |
| 1999-01-01 | 52.400000 |
| 2000-01-01 | 54.710000 |
Fuente: World Bank