| Año | Valor |
|---|---|
| 1990-01-01 | 30.200276 |
| 1991-01-01 | 34.318293 |
| 1992-01-01 | 36.690686 |
| 1993-01-01 | 36.197703 |
| 1994-01-01 | 37.825499 |
| 1995-01-01 | 30.499145 |
| 1996-01-01 | 28.743470 |
| 1997-01-01 | 31.601392 |
| 1998-01-01 | 33.888469 |
| 1999-01-01 | 33.044496 |
| 2000-01-01 | 33.986451 |
| 2001-01-01 | 33.158127 |
| 2002-01-01 | 41.445942 |
| 2003-01-01 | 30.267798 |
| 2004-01-01 | 21.424814 |
| 2005-01-01 | 10.125433 |
| 2006-01-01 | 19.248695 |
| 2007-01-01 | 4.196753 |
| 2008-01-01 | 3.497904 |
| 2009-01-01 | 3.550028 |
Fuente: World Bank