| 年度 | 实际值 |
|---|---|
| 1992 | 12.9 |
| 1993 | 11.8 |
| 1994 | |
| 1995 | 10.37 |
| 1996 | 4.04 |
| 1997 | 4.52 |
| 1998 | 4.12 |
| 1999 | 3.92 |
| 2000 | 4.06 |
| 2001 | 3.47 |
| 2002 | 3.24 |
| 2003 | 3.36 |
| 2004 | 3.66 |
| 2005 | 3.74 |
| 2006 | 5.43 |
| 2007 | 5.24 |
| 2008 | 5.05 |
| 2009 | |
| 2010 | 3.93 |
| 2011 | .9 |
| 2012 | 3.2 |
| 2013 | 5.1 |
| 2014 | 7.6 |
| 2015 | 9 |
| 2016 | 7.09 |
| 2017 | -0.65 |
| 2018 | 6.22 |