| 年度 | 实际值 |
|---|---|
| 1995 | 53.7 |
| 1996 | 51.5 |
| 1997 | 50.66 |
| 1998 | 47.3 |
| 1999 | 48.1 |
| 2000 | 43.6 |
| 2001 | 43.55 |
| 2002 | 41.87 |
| 2003 | 42.69 |
| 2004 | 44.67 |
| 2005 | 46.7 |
| 2006 | 48.65 |
| 2007 | 48.22 |
| 2008 | 49.85 |
| 2009 | |
| 2010 | 46.93 |
| 2011 | 49.35 |
| 2012 | 49.87 |
| 2013 | 48.57 |
| 2014 | 48.24 |
| 2015 | 46.53 |
| 2016 | 45.11 |
| 2017 | 45.47 |
| 2018 | 45.64 |