| 年度 | 实际值 |
|---|---|
| 1992 | 11.1 |
| 1993 | 7.1 |
| 1994 | |
| 1995 | 7.73 |
| 1996 | 7.21 |
| 1997 | |
| 1998 | |
| 1999 | |
| 2000 | 7.01 |
| 2001 | 7.44 |
| 2002 | 9.28 |
| 2003 | 8.92 |
| 2004 | 11.04 |
| 2005 | 6.26 |
| 2006 | 9.69 |
| 2007 | 13.08 |
| 2008 | 6.04 |
| 2009 | |
| 2010 | 6.89 |
| 2011 | 1.3 |
| 2012 | 5.1 |
| 2013 | 15 |
| 2014 | 14.4 |
| 2015 | 13.75 |
| 2016 | 8.42 |
| 2017 | 7.28 |
| 2018 | 10.29 |