| 年度 | 实际值 |
|---|---|
| 1995 | 32.8 |
| 1996 | 23.5 |
| 1997 | 26.34 |
| 1998 | 27.2 |
| 1999 | 30.8 |
| 2000 | 32.1 |
| 2001 | 33.9 |
| 2002 | 34.19 |
| 2003 | 36.79 |
| 2004 | 33.67 |
| 2005 | 38.37 |
| 2006 | 37.35 |
| 2007 | 36.84 |
| 2008 | 36.02 |
| 2009 | |
| 2010 | 33.49 |
| 2011 | 32.64 |
| 2012 | 32.79 |
| 2013 | 33.25 |
| 2014 | 34.26 |
| 2015 | 36.67 |
| 2016 | 38.65 |
| 2017 | |
| 2018 | 40.44 |