| 年度 | 实际值 |
|---|---|
| 1992 | 3.8 |
| 1993 | 3.5 |
| 1994 | |
| 1995 | 4.28 |
| 1996 | 3.43 |
| 1997 | 3.18 |
| 1998 | 6.42 |
| 1999 | 1.52 |
| 2000 | 2.43 |
| 2001 | 1.18 |
| 2002 | 2.02 |
| 2003 | -.7 |
| 2004 | 2.55 |
| 2005 | 1.59 |
| 2006 | 2.17 |
| 2007 | 2.64 |
| 2008 | 1.16 |
| 2009 | |
| 2010 | 2.87 |
| 2011 | 3.2 |
| 2012 | 2.8 |
| 2013 | 3.3 |
| 2014 | 7.8 |
| 2015 | 2.74 |
| 2016 | 7.31 |
| 2017 | 1.01 |
| 2018 | 3.83 |