| 年度 | 实际值 |
|---|---|
| 1995 | 56 |
| 1996 | 56 |
| 1997 | 41.55 |
| 1998 | 56 |
| 1999 | 52.6 |
| 2000 | 52.1 |
| 2001 | 48.08 |
| 2002 | 47.57 |
| 2003 | 52.57 |
| 2004 | 57.46 |
| 2005 | 50.26 |
| 2006 | 46.74 |
| 2007 | 47.17 |
| 2008 | 43.25 |
| 2009 | |
| 2010 | 40.43 |
| 2011 | 53.96 |
| 2012 | 50.83 |
| 2013 | 47.08 |
| 2014 | 47.05 |
| 2015 | 44.57 |
| 2016 | 42.98 |
| 2017 | 43.69 |
| 2018 | 45.05 |