| 年度 | 实际值 |
|---|---|
| 1992 | 53.4 |
| 1993 | |
| 1994 | |
| 1995 | 54 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 53 |
| 2000 | 52.7 |
| 2001 | 52.7 |
| 2002 | 52.77 |
| 2003 | 52.77 |
| 2004 | 53.86 |
| 2005 | 53.84 |
| 2006 | 53.91 |
| 2007 | 54.08 |
| 2008 | 54.17 |
| 2009 | 54.15 |
| 2010 | 53.98 |
| 2011 | 53.94 |
| 2012 | 53.63 |
| 2013 | 53.42 |
| 2014 | 53.19 |
| 2015 | 52.91 |
| 2016 | 52.1 |
| 2017 | 51 |
| 2018 | 50.6427 |