| 年度 | 实际值 |
|---|---|
| 1993 | 16.3 |
| 1994 | |
| 1995 | 19.6 |
| 1996 | 20.9 |
| 1997 | 23.1 |
| 1998 | 24.1 |
| 1999 | 24.8 |
| 2000 | 20.9 |
| 2001 | 1.57333333333333 |
| 2002 | |
| 2003 | 34.6 |
| 2004 | 35.87 |
| 2005 | 36 |
| 2006 | 36.5 |
| 2007 | 37 |
| 2008 | 38.02 |
| 2009 | |
| 2010 | 39.95 |
| 2011 | 44.89 |
| 2012 | 36.94 |
| 2013 | 41.41 |
| 2014 | 40.49 |
| 2015 | 38.41 |
| 2016 | 39.1 |
| 2017 | 42.88 |
| 2018 | 42.2 |