| 年度 | 实际值 |
|---|---|
| 1992 | 14.4 |
| 1993 | 13.7 |
| 1994 | |
| 1995 | 14.37 |
| 1996 | 13.99 |
| 1997 | 13.01 |
| 1998 | 5.41 |
| 1999 | 10.7 |
| 2000 | 10.75 |
| 2001 | 11.36 |
| 2002 | 10.11 |
| 2003 | 9.03 |
| 2004 | 9.13 |
| 2005 | 10.1 |
| 2006 | 19.89 |
| 2007 | 14.53 |
| 2008 | 12.72 |
| 2009 | |
| 2010 | 11.94 |
| 2011 | 15.9 |
| 2012 | .8 |
| 2013 | 12.4 |
| 2014 | 18.5 |
| 2015 | 18.42 |
| 2016 | 18.52 |
| 2017 | 10.9 |
| 2018 | 13.09 |