| 年度 | 实际值 |
|---|---|
| 1992 | 13.7 |
| 1993 | 10.6 |
| 1994 | |
| 1995 | 10.68 |
| 1996 | 10.8 |
| 1997 | 10.65 |
| 1998 | 3.8 |
| 1999 | 11.03 |
| 2000 | 14.61 |
| 2001 | 8.77 |
| 2002 | 8.38 |
| 2003 | 8.85 |
| 2004 | 6.18 |
| 2005 | 4.82 |
| 2006 | 6.7 |
| 2007 | 5.77 |
| 2008 | 8.74 |
| 2009 | |
| 2010 | 9.78 |
| 2011 | 10.1 |
| 2012 | 10.1 |
| 2013 | 11.7 |
| 2014 | 18.3 |
| 2015 | 10.15 |
| 2016 | 12.59 |
| 2017 | 5.52 |
| 2018 | 10.01 |