| 年度 | 实际值 |
|---|---|
| 1995 | 39.4 |
| 1996 | 38.2 |
| 1997 | 36.25 |
| 1998 | 34.2 |
| 1999 | 37.1 |
| 2000 | 38.5 |
| 2001 | 38.93 |
| 2002 | 40.93 |
| 2003 | 41.21 |
| 2004 | 43.34 |
| 2005 | 39.88 |
| 2006 | 41.83 |
| 2007 | 42.5 |
| 2008 | 43.57 |
| 2009 | |
| 2010 | 46.6 |
| 2011 | 47.73 |
| 2012 | 46.85 |
| 2013 | 44.83 |
| 2014 | 31.38 |
| 2015 | 29.88 |
| 2016 | 29.91 |
| 2017 | |
| 2018 | 32.53 |