| 年度 | 实际值 |
|---|---|
| 1992 | 3.8 |
| 1993 | |
| 1994 | |
| 1995 | 3.3 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 3.6327 |
| 2000 | 3.5399 |
| 2001 | 3.4141 |
| 2002 | 3.5666 |
| 2003 | 3.483 |
| 2004 | 3.5172 |
| 2005 | 3.5395 |
| 2006 | 3.7359 |
| 2007 | 3.671 |
| 2008 | 3.5218 |
| 2009 | 3.4848 |
| 2010 | 3.4061 |
| 2011 | 3.7717 |
| 2012 | 3.7205 |
| 2013 | 3.8521 |
| 2014 | 4.4697 |
| 2015 | 3.6216 |