| 年度 | 实际值 |
|---|---|
| 1995 | 50.6 |
| 1996 | 51.2 |
| 1997 | 50.18 |
| 1998 | 50.3 |
| 1999 | 48 |
| 2000 | 48.6 |
| 2001 | 47.51 |
| 2002 | 48.85 |
| 2003 | 50.23 |
| 2004 | 53.23 |
| 2005 | 49.13 |
| 2006 | 49.97 |
| 2007 | 51.78 |
| 2008 | 58.78 |
| 2009 | |
| 2010 | 66.17 |
| 2011 | 63.32 |
| 2012 | 58.22 |
| 2013 | 46.29 |
| 2014 | 40.69 |
| 2015 | 36.78 |
| 2016 | 36.52 |
| 2017 | |
| 2018 | 39.87 |