| 年度 | 实际值 |
|---|---|
| 1992 | 12.5 |
| 1993 | 12.7 |
| 1994 | |
| 1995 | 12.86 |
| 1996 | 12.93 |
| 1997 | 11.18 |
| 1998 | 7.05 |
| 1999 | 7.07 |
| 2000 | 12.78 |
| 2001 | 3.06 |
| 2002 | 3.15 |
| 2003 | 16.9 |
| 2004 | 6.27 |
| 2005 | 5.55 |
| 2006 | 5.24 |
| 2007 | 5.24 |
| 2008 | 5.66 |
| 2009 | |
| 2010 | 5.17 |
| 2011 | 4.6 |
| 2012 | 6.1 |
| 2013 | 6 |
| 2014 | 7.3 |
| 2015 | 7.27 |
| 2016 | 7.18 |
| 2017 | 8.3 |
| 2018 | 11.65 |