| 年度 | 实际值 |
|---|---|
| 1993 | 31.4 |
| 1994 | |
| 1995 | 31.6 |
| 1996 | 30.5 |
| 1997 | 35.8 |
| 1998 | 35.8 |
| 1999 | 36.3 |
| 2000 | 37 |
| 2001 | 2.47333333333333 |
| 2002 | |
| 2003 | 38.03 |
| 2004 | 37.83 |
| 2005 | 38 |
| 2006 | 37.87 |
| 2007 | 42.33 |
| 2008 | 44.66 |
| 2009 | |
| 2010 | 44.58 |
| 2011 | 29.2 |
| 2012 | 29.51 |
| 2013 | 32.51 |
| 2014 | 32.47 |
| 2015 | 32.92 |
| 2016 | 31.5 |
| 2017 | |
| 2018 | 42.71 |