| 年度 | 实际值 |
|---|---|
| 1992 | 9 |
| 1993 | 8.9 |
| 1994 | |
| 1995 | 7.31 |
| 1996 | 11.86 |
| 1997 | 11.35 |
| 1998 | 4.04 |
| 1999 | 7.46 |
| 2000 | 10.32 |
| 2001 | 7.25 |
| 2002 | 9.07 |
| 2003 | 3.68 |
| 2004 | 13.78 |
| 2005 | 9.92 |
| 2006 | 11.86 |
| 2007 | 13.86 |
| 2008 | 12.76 |
| 2009 | |
| 2010 | 10.94 |
| 2011 | 9 |
| 2012 | 4.2 |
| 2013 | 30.7 |
| 2014 | 16.1 |
| 2015 | 12.96 |
| 2016 | 12.7 |
| 2017 | 4.49 |
| 2018 | 13.13 |