| 年度 | 实际值 |
|---|---|
| 1995 | 60 |
| 1996 | 54.6 |
| 1997 | 52.78 |
| 1998 | 51.8 |
| 1999 | 51.7 |
| 2000 | 52.6 |
| 2001 | 51.99 |
| 2002 | 52.08 |
| 2003 | 52.86 |
| 2004 | 54.49 |
| 2005 | 44.09 |
| 2006 | 45.48 |
| 2007 | 45.87 |
| 2008 | 47.06 |
| 2009 | |
| 2010 | 48.09 |
| 2011 | 48.27 |
| 2012 | 47.62 |
| 2013 | 46.19 |
| 2014 | 41.22 |
| 2015 | 37.34 |
| 2016 | 34.89 |
| 2017 | |
| 2018 | 34.32 |