| 年度 | 实际值 |
|---|---|
| 1992 | 5.9 |
| 1993 | 4.6 |
| 1994 | |
| 1995 | 4.01 |
| 1996 | 3.36 |
| 1997 | 4.41 |
| 1998 | 4.99 |
| 1999 | 5.15 |
| 2000 | 6.03 |
| 2001 | 4.46 |
| 2002 | 3.88 |
| 2003 | 5.09 |
| 2004 | 8.01 |
| 2005 | 7.59 |
| 2006 | 9.46 |
| 2007 | 10.35 |
| 2008 | 8.86 |
| 2009 | |
| 2010 | 5.46 |
| 2011 | 6.8 |
| 2012 | 1.5 |
| 2013 | 10.9 |
| 2014 | 11.9 |
| 2015 | 10.39 |
| 2016 | 10.83 |
| 2017 | 12.56 |
| 2018 | 10.03 |