| 年度 | 实际值 |
|---|---|
| 1992 | 8.9 |
| 1993 | 9 |
| 1994 | |
| 1995 | 10.26 |
| 1996 | 9.01 |
| 1997 | |
| 1998 | |
| 1999 | |
| 2000 | 14.52 |
| 2001 | 9.01 |
| 2002 | 8.33 |
| 2003 | 6.45 |
| 2004 | 7.54 |
| 2005 | 6.2 |
| 2006 | 5.4 |
| 2007 | 7.64 |
| 2008 | 5.42 |
| 2009 | |
| 2010 | 10.41 |
| 2011 | 9.3 |
| 2012 | 10.9 |
| 2013 | 10.2 |
| 2014 | 11.8 |
| 2015 | 27.75 |
| 2016 | 13.44 |
| 2017 | 7.28 |
| 2018 | 14.64 |