| 年度 | 实际值 |
|---|---|
| 1995 | 32.1 |
| 1996 | 31.7 |
| 1997 | 31.81 |
| 1998 | 31.9 |
| 1999 | 36.2 |
| 2000 | 38.9 |
| 2001 | 37.5 |
| 2002 | 37.57 |
| 2003 | 34.78 |
| 2004 | 32.09 |
| 2005 | 30.81 |
| 2006 | 29.79 |
| 2007 | 27.1 |
| 2008 | 24.83 |
| 2009 | |
| 2010 | 33.28 |
| 2011 | 30.18 |
| 2012 | 31.42 |
| 2013 | 32.38 |
| 2014 | 33.2 |
| 2015 | 35.82 |
| 2016 | 37.68 |
| 2017 | |
| 2018 | 45.68 |