| 年度 | 实际值 |
|---|---|
| 1995 | 20.7 |
| 1996 | 23.6 |
| 1997 | 26.1 |
| 1998 | 28.6 |
| 1999 | 31.4 |
| 2000 | 32.3 |
| 2001 | 33.38 |
| 2002 | 33.38 |
| 2003 | 33.42 |
| 2004 | 30.09 |
| 2005 | 35.13 |
| 2006 | 33.27 |
| 2007 | 31.56 |
| 2008 | 31.2 |
| 2009 | |
| 2010 | 32.91 |
| 2011 | 31.39 |
| 2012 | 31.49 |
| 2013 | 33.86 |
| 2014 | 36.97 |
| 2015 | 41.68 |
| 2016 | 45.71 |
| 2017 | |
| 2018 | 44.69 |