| 年度 | 实际值 |
|---|---|
| 1995 | 68.7 |
| 1996 | 65.3 |
| 1997 | 65.34 |
| 1998 | 60 |
| 1999 | 55.1 |
| 2000 | 54 |
| 2001 | 56.71 |
| 2002 | 57.01 |
| 2003 | 60.75 |
| 2004 | 63.2 |
| 2005 | 56.13 |
| 2006 | 54.63 |
| 2007 | 54.1 |
| 2008 | 53.88 |
| 2009 | |
| 2010 | 51.14 |
| 2011 | 53.79 |
| 2012 | 53.87 |
| 2013 | 50.07 |
| 2014 | 47.41 |
| 2015 | 45.09 |
| 2016 | 38.91 |
| 2017 | 38.54 |
| 2018 | 51.12 |