| 年度 | 实际值 |
|---|---|
| 1992 | 27.7 |
| 1993 | |
| 1994 | |
| 1995 | 28.3 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 28.15 |
| 2000 | 281475 |
| 2001 | 281398 |
| 2002 | 24.0036 |
| 2003 | 25.0623 |
| 2004 | 27.688 |
| 2005 | 27.4733 |
| 2006 | 27.52 |
| 2007 | 27.68 |
| 2008 | 27.89 |
| 2009 | 28.2583 |
| 2010 | 28.2627 |
| 2011 | 27.6814 |
| 2012 | 27.86 |
| 2013 | 28.27 |
| 2014 | 28.54 |
| 2015 | 23.68 |
| 2016 | 22.52 |