| 年度 | 实际值 |
|---|---|
| 1992 | 7.4 |
| 1993 | 6.5 |
| 1994 | |
| 1995 | 7.02 |
| 1996 | 9.85 |
| 1997 | 10.06 |
| 1998 | 3.8 |
| 1999 | 9.05 |
| 2000 | 15.7 |
| 2001 | 8.9 |
| 2002 | 11.74 |
| 2003 | 7.67 |
| 2004 | 7.06 |
| 2005 | 13.3 |
| 2006 | 11.51 |
| 2007 | 11.21 |
| 2008 | 10.96 |
| 2009 | |
| 2010 | 14.19 |
| 2011 | 9.3 |
| 2012 | 7.3 |
| 2013 | 8.8 |
| 2014 | 22.1 |
| 2015 | 10.07 |
| 2016 | 10.4 |
| 2017 | 3.57 |
| 2018 | 10.65 |