| 年度 | 实际值 |
|---|---|
| 1992 | 2.5 |
| 1993 | 6 |
| 1994 | |
| 1995 | 12.88 |
| 1996 | 10.91 |
| 1997 | 12.17 |
| 1998 | 2.35 |
| 1999 | 6.19 |
| 2000 | 16.01 |
| 2001 | 5.55 |
| 2002 | 6.16 |
| 2003 | 5.14 |
| 2004 | 5.04 |
| 2005 | 7.21 |
| 2006 | 7.38 |
| 2007 | 7.34 |
| 2008 | 6.16 |
| 2009 | |
| 2010 | 6.03 |
| 2011 | 6.2 |
| 2012 | |
| 2013 | 10 |
| 2014 | 9.7 |
| 2015 | 9.58 |
| 2016 | 9.86 |
| 2017 | 2.12 |
| 2018 | 7.66 |