| 年度 | 实际值 |
|---|---|
| 1992 | 10.7 |
| 1993 | 9.4 |
| 1994 | |
| 1995 | 10.54 |
| 1996 | 10.83 |
| 1997 | 8.41 |
| 1998 | 4.99 |
| 1999 | 11.09 |
| 2000 | 19.41 |
| 2001 | 5.9 |
| 2002 | 6.91 |
| 2003 | 6.93 |
| 2004 | 4.59 |
| 2005 | 4.28 |
| 2006 | 6.82 |
| 2007 | .46 |
| 2008 | 7.47 |
| 2009 | |
| 2010 | 7.04 |
| 2011 | 6.8 |
| 2012 | 5.7 |
| 2013 | 8.5 |
| 2014 | 9.1 |
| 2015 | 4.46 |
| 2016 | 8.45 |
| 2017 | 3.62 |
| 2018 | 9.89 |