| 年度 | 实际值 |
|---|---|
| 1995 | 25.8 |
| 1996 | 29.7 |
| 1997 | 29.81 |
| 1998 | 29.3 |
| 1999 | 30.2 |
| 2000 | 33.5 |
| 2001 | 36.7 |
| 2002 | 36.16 |
| 2003 | 34.36 |
| 2004 | 31.93 |
| 2005 | 32.91 |
| 2006 | 31.88 |
| 2007 | |
| 2008 | 32.16 |
| 2009 | |
| 2010 | 36.68 |
| 2011 | 35.6 |
| 2012 | 34.29 |
| 2013 | 35.72 |
| 2014 | 36.37 |
| 2015 | 40.68 |
| 2016 | 35.55 |
| 2017 | 34.22 |
| 2018 | 40.06 |