| 年度 | 实际值 |
|---|---|
| 1995 | 34.7 |
| 1996 | 33.4 |
| 1997 | 43.94 |
| 1998 | 37.2 |
| 1999 | 36.9 |
| 2000 | 37 |
| 2001 | 36.36 |
| 2002 | 36.48 |
| 2003 | 35.45 |
| 2004 | 33.2 |
| 2005 | 38.27 |
| 2006 | 36.89 |
| 2007 | 34.83 |
| 2008 | 28.12 |
| 2009 | |
| 2010 | 41.95 |
| 2011 | 40.81 |
| 2012 | 42.27 |
| 2013 | 41.1 |
| 2014 | 41.19 |
| 2015 | 43.8 |
| 2016 | 43.89 |
| 2017 | 42.67 |
| 2018 | 41.31 |