| 年度 | 实际值 |
|---|---|
| 1992 | 9.6 |
| 1993 | 8 |
| 1994 | |
| 1995 | 7.74 |
| 1996 | 6.68 |
| 1997 | |
| 1998 | |
| 1999 | 5.98 |
| 2000 | 5.46 |
| 2001 | 4.01 |
| 2002 | 4.83 |
| 2003 | 4.82 |
| 2004 | 4.86 |
| 2005 | 5.9 |
| 2006 | 4.29 |
| 2007 | 8.58 |
| 2008 | 9.16 |
| 2009 | |
| 2010 | 11.07 |
| 2011 | 12.5 |
| 2012 | 12.8 |
| 2013 | 15.4 |
| 2014 | 11.9 |
| 2015 | 12.14 |
| 2016 | 6.9 |
| 2017 | -16.27 |
| 2018 | 8.77 |