| 年度 | 实际值 |
|---|---|
| 1993 | 20.5 |
| 1994 | |
| 1995 | 18.3 |
| 1996 | 21.3 |
| 1997 | |
| 1998 | 17 |
| 1999 | 24.2 |
| 2000 | 26.2 |
| 2001 | .953333333333333 |
| 2002 | |
| 2003 | 27.5 |
| 2004 | 29.65 |
| 2005 | 29 |
| 2006 | 29.06 |
| 2007 | 27.37 |
| 2008 | 41.17 |
| 2009 | |
| 2010 | 41.82 |
| 2011 | 39.66 |
| 2012 | 44.85 |
| 2013 | 42.42 |
| 2014 | 42.29 |
| 2015 | 42.46 |
| 2016 | 42.46 |
| 2017 | 42.46 |
| 2018 | 43.8 |