| 年度 | 实际值 |
|---|---|
| 1993 | 34.2 |
| 1994 | |
| 1995 | 33.8 |
| 1996 | 36.8 |
| 1997 | 38.2 |
| 1998 | 37 |
| 1999 | 37.2 |
| 2000 | 37.1 |
| 2001 | 2.46666666666667 |
| 2002 | |
| 2003 | 31.52 |
| 2004 | 33.45 |
| 2005 | 36 |
| 2006 | 39.77 |
| 2007 | 37.32 |
| 2008 | 39.74 |
| 2009 | |
| 2010 | 34.6 |
| 2011 | 48 |
| 2012 | 42.14 |
| 2013 | 41.35 |
| 2014 | 41.68 |
| 2015 | 38.71 |
| 2016 | 41.95 |
| 2017 | 42.08 |
| 2018 | 42.67 |