| 年度 | 实际值 |
|---|---|
| 1995 | 33.1 |
| 1996 | 34.9 |
| 1997 | 10.38 |
| 1998 | 37 |
| 1999 | 37.9 |
| 2000 | 34.3 |
| 2001 | 33.66 |
| 2002 | 33.38 |
| 2003 | 32.26 |
| 2004 | 30.37 |
| 2005 | 38.39 |
| 2006 | 37.52 |
| 2007 | 36.63 |
| 2008 | 34.94 |
| 2009 | |
| 2010 | 29.94 |
| 2011 | 25.75 |
| 2012 | 25.78 |
| 2013 | 30.61 |
| 2014 | 47.48 |
| 2015 | 41.76 |
| 2016 | 41.24 |
| 2017 | 43.03 |
| 2018 | 43.46 |