| 年度 | 实际值 |
|---|---|
| 1995 | 52.7 |
| 1996 | 51.1 |
| 1997 | 54.12 |
| 1998 | 53.8 |
| 1999 | 53 |
| 2000 | 52.9 |
| 2001 | 52.72 |
| 2002 | 54.2 |
| 2003 | 55.31 |
| 2004 | 56.85 |
| 2005 | 54.31 |
| 2006 | 55.46 |
| 2007 | 49.83 |
| 2008 | 55.02 |
| 2009 | |
| 2010 | 54.41 |
| 2011 | 58.27 |
| 2012 | 50.97 |
| 2013 | 50.82 |
| 2014 | 51.42 |
| 2015 | 51.47 |
| 2016 | 50.57 |
| 2017 | 50.04 |
| 2018 | 48.7 |