| 年度 | 实际值 |
|---|---|
| 1995 | 58 |
| 1996 | 54.3 |
| 1997 | 53.44 |
| 1998 | 46.5 |
| 1999 | 45.3 |
| 2000 | 45.8 |
| 2001 | 42.94 |
| 2002 | 44.73 |
| 2003 | 49.79 |
| 2004 | 50.48 |
| 2005 | 52.37 |
| 2006 | 52.93 |
| 2007 | 52.15 |
| 2008 | 50.8 |
| 2009 | |
| 2010 | 47.62 |
| 2011 | 45.54 |
| 2012 | 43.46 |
| 2013 | 52.65 |
| 2014 | 51.3 |
| 2015 | 49.63 |
| 2016 | 48.86 |
| 2017 | 47.84 |
| 2018 | 47.39 |