| 年度 | 实际值 |
|---|---|
| 1995 | 51.7 |
| 1996 | 56.2 |
| 1997 | 48.96 |
| 1998 | 57.7 |
| 1999 | 57.7 |
| 2000 | 57.3 |
| 2001 | 54.92 |
| 2002 | 54.77 |
| 2003 | 53.4 |
| 2004 | 54.7 |
| 2005 | 54.53 |
| 2006 | 57.33 |
| 2007 | 57.43 |
| 2008 | 57.23 |
| 2009 | |
| 2010 | 54.99 |
| 2011 | 53.82 |
| 2012 | 53.28 |
| 2013 | 52.55 |
| 2014 | 49.12 |
| 2015 | 47.32 |
| 2016 | 45.82 |
| 2017 | 45.04 |
| 2018 | 44.33 |