| 年度 | 实际值 |
|---|---|
| 1992 | 74.68 |
| 1993 | 75.2 |
| 1994 | 75.89 |
| 1995 | 76.45 |
| 1996 | 77.01 |
| 1997 | 77.62 |
| 1998 | 77.83 |
| 1999 | 77.83 |
| 2000 | 78.22 |
| 2001 | 78.39 |
| 2002 | 78.37 |
| 2003 | 78.2 |
| 2004 | 77.99 |
| 2005 | 78.18 |
| 2006 | 78.25 |
| 2007 | 78.04 |
| 2008 | 77.89 |
| 2009 | |
| 2010 | 77.59 |
| 2011 | 78.1 |
| 2012 | 77.9 |
| 2013 | 77.5 |
| 2014 | 77.2 |
| 2015 | 76.42 |
| 2016 | 76 |
| 2017 | 75 |
| 2018 | 74 |