| 年度 | 实际值 |
|---|---|
| 1992 | 58.1 |
| 1993 | |
| 1994 | |
| 1995 | 58.7 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 59.5 |
| 2000 | 59.6 |
| 2001 | 60 |
| 2002 | 59.4 |
| 2003 | 59 |
| 2004 | 59 |
| 2005 | 59 |
| 2006 | 60 |
| 2007 | 59.71 |
| 2008 | 56.8 |
| 2009 | 56.6013 |
| 2010 | 56.5204 |
| 2011 | 56.6186 |
| 2012 | 56.2447 |
| 2013 | 56.42 |
| 2014 | 56.56 |
| 2015 | 56.46 |
| 2016 | 56.5 |
| 2017 | 56.4 |
| 2018 | 56.03 |