| 年度 | 实际值 |
|---|---|
| 1992 | 38.4 |
| 1993 | |
| 1994 | |
| 1995 | 39 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 39.4 |
| 2000 | 39.56 |
| 2001 | 39.66 |
| 2002 | 39.45 |
| 2003 | 39.37 |
| 2004 | 39.44 |
| 2005 | 39.53 |
| 2006 | 39.69 |
| 2007 | 39.82 |
| 2008 | 39.91 |
| 2009 | 40.07 |
| 2010 | 40.25 |
| 2011 | 40.47 |
| 2012 | 40.42 |
| 2013 | 40.59 |
| 2014 | 40.84 |
| 2015 | 40.94 |
| 2016 | 41.1439 |
| 2017 | 41 |