| 年度 | 实际值 |
|---|---|
| 1995 | 51.3 |
| 1996 | 52.5 |
| 1997 | 52.92 |
| 1998 | 53.4 |
| 1999 | 48.2 |
| 2000 | 49.5 |
| 2001 | 49.94 |
| 2002 | 51.68 |
| 2003 | 56.39 |
| 2004 | 61.36 |
| 2005 | 63.33 |
| 2006 | 63.53 |
| 2007 | 63.85 |
| 2008 | 62.79 |
| 2009 | |
| 2010 | 60.08 |
| 2011 | 58.93 |
| 2012 | 58.21 |
| 2013 | 56.68 |
| 2014 | 54.33 |
| 2015 | 52.69 |
| 2016 | 51.24 |
| 2017 | |
| 2018 | 50.77 |