| Año | Valor |
|---|---|
| 1990-01-01 | 14.208501 |
| 1991-01-01 | 14.533219 |
| 1992-01-01 | 13.948002 |
| 1993-01-01 | 13.566635 |
| 1994-01-01 | 12.834505 |
| 1995-01-01 | 11.950295 |
| 1996-01-01 | 11.154134 |
| 1997-01-01 | 10.694223 |
| 1998-01-01 | 11.078443 |
| 1999-01-01 | 11.368045 |
| 2000-01-01 | 14.478368 |
| 2001-01-01 | 13.822290 |
| 2002-01-01 | 11.909620 |
| 2003-01-01 | 11.933607 |
| 2004-01-01 | 12.247580 |
| 2005-01-01 | 11.593573 |
| 2006-01-01 | 11.926008 |
| 2007-01-01 | 12.216572 |
| 2008-01-01 | 12.707772 |
| 2009-01-01 | 12.608495 |
Fuente: World Bank