| 年度 | 实际值 |
|---|---|
| 1992 | 9.7 |
| 1993 | 9.8 |
| 1994 | |
| 1995 | 10.46 |
| 1996 | 9.92 |
| 1997 | 9.52 |
| 1998 | 5.28 |
| 1999 | 8.78 |
| 2000 | 11.05 |
| 2001 | 9.22 |
| 2002 | 8.73 |
| 2003 | 8.73 |
| 2004 | 9.48 |
| 2005 | 7.76 |
| 2006 | 13.37 |
| 2007 | 11.21 |
| 2008 | 5.99 |
| 2009 | |
| 2010 | 15.27 |
| 2011 | 7.3 |
| 2012 | 6.4 |
| 2013 | 6.2 |
| 2014 | 7.9 |
| 2015 | 7.95 |
| 2016 | 8.74 |
| 2017 | 12.58 |
| 2018 | 8.88 |