| 年度 | 实际值 |
|---|---|
| 1995 | 67.6 |
| 1996 | 62.9 |
| 1997 | 67.31 |
| 1998 | 66.8 |
| 1999 | 66 |
| 2000 | 66.1 |
| 2001 | 62.94 |
| 2002 | 57.27 |
| 2003 | 58.76 |
| 2004 | 58.49 |
| 2005 | 52.78 |
| 2006 | 53.33 |
| 2007 | 48.68 |
| 2008 | 48.77 |
| 2009 | |
| 2010 | 52.28 |
| 2011 | 52.53 |
| 2012 | 52.16 |
| 2013 | 46.97 |
| 2014 | 45.19 |
| 2015 | 45.81 |
| 2016 | 44.59 |
| 2017 | 40.7 |
| 2018 | 40.69 |