| 年度 | 实际值 |
|---|---|
| 1992 | 12.5 |
| 1993 | 13.3 |
| 1994 | |
| 1995 | 13.53 |
| 1996 | 13.5 |
| 1997 | 10.31 |
| 1998 | 5.38 |
| 1999 | 5.26 |
| 2000 | 5.25 |
| 2001 | 2.65 |
| 2002 | 5.58 |
| 2003 | 4.13 |
| 2004 | 5.51 |
| 2005 | 3.56 |
| 2006 | 4.44 |
| 2007 | 3.9 |
| 2008 | 9.71 |
| 2009 | |
| 2010 | 10.63 |
| 2011 | 10.3 |
| 2012 | 3.3 |
| 2013 | 19.3 |
| 2014 | 11.3 |
| 2015 | 22.95 |
| 2016 | 14.31 |
| 2017 | 14.09 |
| 2018 | 14.93 |