| 年度 | 实际值 |
|---|---|
| 1993 | 27.5 |
| 1994 | |
| 1995 | 13.9 |
| 1996 | 14 |
| 1997 | 16.1 |
| 1998 | 21.6 |
| 1999 | 23.1 |
| 2000 | 22.5 |
| 2001 | 1.39333333333333 |
| 2002 | |
| 2003 | 28 |
| 2004 | 28.04 |
| 2005 | 24 |
| 2006 | 33.61 |
| 2007 | 32.98 |
| 2008 | 38.26 |
| 2009 | |
| 2010 | 39.08 |
| 2011 | 36.57 |
| 2012 | 35.47 |
| 2013 | 35.13 |
| 2014 | 33.25 |
| 2015 | 33.27 |
| 2016 | 33.05 |
| 2017 | 36.12 |
| 2018 | 40.37 |