| 年度 | 实际值 |
|---|---|
| 1993 | 26.8 |
| 1994 | |
| 1995 | 31.2 |
| 1996 | 28.8 |
| 1997 | 30.5 |
| 1998 | 29.1 |
| 1999 | 29.1 |
| 2000 | 30.1 |
| 2001 | 2.06666666666667 |
| 2002 | |
| 2003 | 37.51 |
| 2004 | 34.5 |
| 2005 | 41 |
| 2006 | 35.23 |
| 2007 | 36.57 |
| 2008 | 37.34 |
| 2009 | |
| 2010 | 39 |
| 2011 | 40.5 |
| 2012 | 42 |
| 2013 | 42.31 |
| 2014 | 42.71 |
| 2015 | 42.81 |
| 2016 | 44.13 |
| 2017 | 44.3 |
| 2018 | 44.5 |