| 年度 | 实际值 |
|---|---|
| 1993 | 32.2 |
| 1994 | |
| 1995 | 34.1 |
| 1996 | 34.2 |
| 1997 | 34.7 |
| 1998 | 30.1 |
| 1999 | 35.2 |
| 2000 | 35.2 |
| 2001 | 2.46666666666667 |
| 2002 | |
| 2003 | 42 |
| 2004 | 42 |
| 2005 | 43 |
| 2006 | 42.54 |
| 2007 | 42.08 |
| 2008 | 41.08 |
| 2009 | |
| 2010 | 40.54 |
| 2011 | 41.34 |
| 2012 | 41.21 |
| 2013 | 41.26 |
| 2014 | 43.78 |
| 2015 | 44.57 |
| 2016 | 43.72 |
| 2017 | 44.21 |
| 2018 | 44.26 |