| 年度 | 实际值 |
|---|---|
| 1995 | 52.9 |
| 1996 | 51.6 |
| 1997 | 53.68 |
| 1998 | 53.8 |
| 1999 | 51.7 |
| 2000 | 55.2 |
| 2001 | 54.54 |
| 2002 | 52.97 |
| 2003 | 54.07 |
| 2004 | 53.68 |
| 2005 | 53.84 |
| 2006 | 50.45 |
| 2007 | 48.98 |
| 2008 | 50.57 |
| 2009 | |
| 2010 | 46.33 |
| 2011 | 49.67 |
| 2012 | 48.11 |
| 2013 | 46.85 |
| 2014 | 43.43 |
| 2015 | 39.31 |
| 2016 | 36.91 |
| 2017 | 33.79 |
| 2018 | 31.67 |