| 年度 | 实际值 |
|---|---|
| 1993 | 21.9 |
| 1994 | |
| 1995 | 22 |
| 1996 | 19.9 |
| 1997 | 20.5 |
| 1998 | 33.1 |
| 1999 | 33.5 |
| 2000 | 34.4 |
| 2001 | 2.31333333333333 |
| 2002 | |
| 2003 | 36.57 |
| 2004 | 35.91 |
| 2005 | 37 |
| 2006 | 38.14 |
| 2007 | 38.5 |
| 2008 | 38.6 |
| 2009 | |
| 2010 | 39.91 |
| 2011 | 40.04 |
| 2012 | 40.03 |
| 2013 | 40.27 |
| 2014 | 40.47 |
| 2015 | 40.44 |
| 2016 | 40.73 |
| 2017 | 39.96 |
| 2018 | 40.63 |