| 年度 | 实际值 |
|---|---|
| 1992 | 30 |
| 1993 | |
| 1994 | |
| 1995 | 28.9 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 19.1908 |
| 2000 | 19.1736 |
| 2001 | 29.142 |
| 2002 | 29.2123 |
| 2003 | 29.2 |
| 2004 | 29.5 |
| 2005 | 29.5668 |
| 2006 | 33.1574 |
| 2007 | 33.5878 |
| 2008 | 33.8067 |
| 2009 | 33.8013 |
| 2010 | 34.7194 |
| 2011 | 34.971 |
| 2012 | 35 |
| 2013 | 35.393 |
| 2014 | 27.929 |
| 2015 | 28.2647 |