| Año | Valor |
|---|---|
| 1990-01-01 | 41.476566 |
| 1991-01-01 | 38.181019 |
| 1992-01-01 | 40.422886 |
| 1993-01-01 | 39.683138 |
| 1994-01-01 | 49.822946 |
| 1995-01-01 | 54.455118 |
| 1996-01-01 | 52.964793 |
| 1997-01-01 | 52.390553 |
| 1998-01-01 | 54.797844 |
| 1999-01-01 | 50.734347 |
| 2000-01-01 | 47.603093 |
| 2001-01-01 | 43.983924 |
| 2002-01-01 | 44.850657 |
| 2003-01-01 | 51.759025 |
| 2004-01-01 | 50.176211 |
| 2005-01-01 | 57.581926 |
| 2006-01-01 | 54.344360 |
| 2007-01-01 | 54.577142 |
| 2008-01-01 | 58.337540 |
| 2009-01-01 | 60.122010 |
Fuente: World Bank