| 年度 | 实际值 |
|---|---|
| 1992 | 24.7 |
| 1993 | |
| 1994 | |
| 1995 | 23.8 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 14.7912 |
| 2000 | 14.6783 |
| 2001 | 24.0589 |
| 2002 | 23.9734 |
| 2003 | 24.5155 |
| 2004 | 24.3725 |
| 2005 | 23.8149 |
| 2006 | 23.6648 |
| 2007 | 23.6944 |
| 2008 | 23.912 |
| 2009 | 24.4329 |
| 2010 | 24.5584 |
| 2011 | 24.3797 |
| 2012 | 24.3821 |
| 2013 | 23.8409 |
| 2014 | 24.2573 |
| 2015 | 22.2335 |