| 年度 | 实际值 |
|---|---|
| 1995 | 30.9 |
| 1996 | 33.5 |
| 1997 | 29.57 |
| 1998 | 37.8 |
| 1999 | 40.3 |
| 2000 | 33.3 |
| 2001 | 35.11 |
| 2002 | 36.79 |
| 2003 | 43.61 |
| 2004 | 39.3 |
| 2005 | 43.27 |
| 2006 | 35.1 |
| 2007 | 33.59 |
| 2008 | 32.9 |
| 2009 | |
| 2010 | 42.09 |
| 2011 | 38.29 |
| 2012 | 41.51 |
| 2013 | 35.94 |
| 2014 | 36.78 |
| 2015 | 39.37 |
| 2016 | 40.02 |
| 2017 | 39.53 |
| 2018 | 43.45 |