| 年度 | 实际值 |
|---|---|
| 1995 | 38.5 |
| 1996 | 35.4 |
| 1997 | 25.53 |
| 1998 | 36.8 |
| 1999 | |
| 2000 | 31.8 |
| 2001 | 32.55 |
| 2002 | 31.06 |
| 2003 | 29.47 |
| 2004 | 27.77 |
| 2005 | 31.9 |
| 2006 | 32.71 |
| 2007 | 32.24 |
| 2008 | 37.02 |
| 2009 | |
| 2010 | 43.38 |
| 2011 | 43.86 |
| 2012 | 42.89 |
| 2013 | 41.94 |
| 2014 | 43.35 |
| 2015 | 44.8 |
| 2016 | 46.36 |
| 2017 | 46.41 |
| 2018 | 45.27 |