| 年度 | 实际值 |
|---|---|
| 1992 | 33.1 |
| 1993 | |
| 1994 | |
| 1995 | 33.2 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 32.66 |
| 2000 | 326924 |
| 2001 | 327080 |
| 2002 | 29.8378 |
| 2003 | 29.6474 |
| 2004 | 29.4833 |
| 2005 | 29.4154 |
| 2006 | 29.33 |
| 2007 | 29.36 |
| 2008 | 29.52 |
| 2009 | 29.7405 |
| 2010 | 29.8361 |
| 2011 | 29.7533 |
| 2012 | 29.5 |
| 2013 | 30.16 |
| 2014 | 29.25 |
| 2015 | 24.41 |
| 2016 | 24.3 |