| 年度 | 实际值 |
|---|---|
| 1993 | 26.3 |
| 1994 | |
| 1995 | 29.1 |
| 1996 | 30.1 |
| 1997 | 31.1 |
| 1998 | 32.1 |
| 1999 | 32 |
| 2000 | 32.8 |
| 2001 | 2.23333333333333 |
| 2002 | |
| 2003 | 32.93 |
| 2004 | 34.5 |
| 2005 | 35 |
| 2006 | 35.73 |
| 2007 | 33.55 |
| 2008 | 34.14 |
| 2009 | |
| 2010 | 34.34 |
| 2011 | 39.42 |
| 2012 | 40.67 |
| 2013 | 40.97 |
| 2014 | 42.05 |
| 2015 | 42 |
| 2016 | 42.54 |
| 2017 | 42.9 |
| 2018 | 42.72 |