| 年度 | 实际值 |
|---|---|
| 1995 | 39.3 |
| 1996 | 40 |
| 1997 | 39.3 |
| 1998 | 41.3 |
| 1999 | 41.3 |
| 2000 | 35.7 |
| 2001 | 35.59 |
| 2002 | 35.58 |
| 2003 | 37.86 |
| 2004 | 40.47 |
| 2005 | 34.49 |
| 2006 | 38.65 |
| 2007 | 44.58 |
| 2008 | 44.26 |
| 2009 | |
| 2010 | 41.18 |
| 2011 | 42.47 |
| 2012 | 44.18 |
| 2013 | 43.11 |
| 2014 | 44.11 |
| 2015 | 42.56 |
| 2016 | 41.38 |
| 2017 | |
| 2018 | 37.78 |