| 年度 | 实际值 |
|---|---|
| 1992 | 39.2 |
| 1993 | |
| 1994 | |
| 1995 | 39.6 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 40.4 |
| 2000 | 40.4 |
| 2001 | 40.49 |
| 2002 | 40.69 |
| 2003 | 40.72 |
| 2004 | 40.59 |
| 2005 | 40.05 |
| 2006 | 40.07 |
| 2007 | 40.17 |
| 2008 | 40.31 |
| 2009 | 40.31 |
| 2010 | 40.31 |
| 2011 | 40.41 |
| 2012 | 40.37 |
| 2013 | 40.4 |
| 2014 | 40.42 |
| 2015 | 40.51 |
| 2016 | 40.6753 |
| 2017 | 41 |