| 年度 | 实际值 |
|---|---|
| 1995 | 54.5 |
| 1996 | 54.2 |
| 1997 | 52.6 |
| 1998 | 49.6 |
| 1999 | 49.2 |
| 2000 | 50.1 |
| 2001 | 48.84 |
| 2002 | 48.77 |
| 2003 | 51.05 |
| 2004 | 53.63 |
| 2005 | 56.09 |
| 2006 | 57.36 |
| 2007 | 57.66 |
| 2008 | 60.49 |
| 2009 | |
| 2010 | 53.58 |
| 2011 | 52.5 |
| 2012 | 51.41 |
| 2013 | 50.4 |
| 2014 | 49.5 |
| 2015 | 46.58 |
| 2016 | 42.33 |
| 2017 | 40.94 |
| 2018 | 40.46 |