| 年度 | 实际值 |
|---|---|
| 1993 | 16.6 |
| 1994 | |
| 1995 | 17.5 |
| 1996 | 16.3 |
| 1997 | 16.4 |
| 1998 | 14.8 |
| 1999 | 17.4 |
| 2000 | 17.8 |
| 2001 | 1.10666666666667 |
| 2002 | |
| 2003 | 17 |
| 2004 | 23.49 |
| 2005 | 39 |
| 2006 | 30.1 |
| 2007 | 27 |
| 2008 | 30.37 |
| 2009 | |
| 2010 | 37.14 |
| 2011 | 40.02 |
| 2012 | 40 |
| 2013 | 39.71 |
| 2014 | 40.03 |
| 2015 | 39.88 |
| 2016 | 41.08 |
| 2017 | |
| 2018 | 41.69 |