| 年度 | 实际值 |
|---|---|
| 1992 | 13.3 |
| 1993 | 14.9 |
| 1994 | |
| 1995 | 6.52 |
| 1996 | 3.02 |
| 1997 | |
| 1998 | |
| 1999 | 4.35 |
| 2000 | 4.3 |
| 2001 | 3.86 |
| 2002 | 2.78 |
| 2003 | 4.26 |
| 2004 | 2.67 |
| 2005 | 6.71 |
| 2006 | 8.46 |
| 2007 | 8.14 |
| 2008 | 7.44 |
| 2009 | |
| 2010 | 7.25 |
| 2011 | 11.6 |
| 2012 | 11.3 |
| 2013 | 12.8 |
| 2014 | 15 |
| 2015 | 24.23 |
| 2016 | 11.68 |
| 2017 | 7.5 |
| 2018 | 11.36 |