| 年度 | 实际值 |
|---|---|
| 1995 | 30.4 |
| 1996 | 33.3 |
| 1997 | 35.67 |
| 1998 | 37.9 |
| 1999 | 37.9 |
| 2000 | 37.6 |
| 2001 | 37.93 |
| 2002 | 37.99 |
| 2003 | 37.09 |
| 2004 | 31.84 |
| 2005 | 34.77 |
| 2006 | 30.14 |
| 2007 | 29.6 |
| 2008 | 30.3 |
| 2009 | |
| 2010 | 25.19 |
| 2011 | 23.36 |
| 2012 | 24.66 |
| 2013 | 26.1 |
| 2014 | 26.98 |
| 2015 | 33.07 |
| 2016 | 35.38 |
| 2017 | |
| 2018 | 37.66 |