| 年度 | 实际值 |
|---|---|
| 1993 | 24.7 |
| 1994 | |
| 1995 | 23.2 |
| 1996 | 18.9 |
| 1997 | |
| 1998 | |
| 1999 | |
| 2000 | 23.5 |
| 2001 | 2.26666666666667 |
| 2002 | |
| 2003 | 23.08 |
| 2004 | 21.41 |
| 2005 | 25 |
| 2006 | 29.74 |
| 2007 | 35.53 |
| 2008 | 41.03 |
| 2009 | |
| 2010 | 41.78 |
| 2011 | 45.19 |
| 2012 | 57.11 |
| 2013 | 56.86 |
| 2014 | 45.79 |
| 2015 | 45.82 |
| 2016 | 46.16 |
| 2017 | 45.81 |
| 2018 | 45.81 |