| 年度 | 实际值 |
|---|---|
| 1992 | 10.8 |
| 1993 | 13.3 |
| 1994 | |
| 1995 | 7.31 |
| 1996 | 6.01 |
| 1997 | 7.05 |
| 1998 | 4.24 |
| 1999 | 7.36 |
| 2000 | 12.79 |
| 2001 | 5.57 |
| 2002 | 4.88 |
| 2003 | 6.22 |
| 2004 | 4.55 |
| 2005 | 3.77 |
| 2006 | 8.19 |
| 2007 | 9.04 |
| 2008 | 7.41 |
| 2009 | |
| 2010 | 11.35 |
| 2011 | 10 |
| 2012 | |
| 2013 | 14.4 |
| 2014 | 12.4 |
| 2015 | 9.73 |
| 2016 | 11.55 |
| 2017 | 3.05 |
| 2018 | 7.25 |