| 年度 | 实际值 |
|---|---|
| 1992 | 22.6 |
| 1993 | |
| 1994 | |
| 1995 | 23.2 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 15.3024 |
| 2000 | 14.6386 |
| 2001 | 22.5564 |
| 2002 | 22.5704 |
| 2003 | 22.2625 |
| 2004 | 22.3006 |
| 2005 | 21.9845 |
| 2006 | 21.5304 |
| 2007 | 20.8159 |
| 2008 | 24.106 |
| 2009 | 18.16 |
| 2010 | 20.3822 |
| 2011 | 20.381 |
| 2012 | 19.9705 |
| 2013 | 19.4422 |
| 2014 | 23.1977 |
| 2015 | 22.5348 |