| 年度 | 实际值 |
|---|---|
| 1993 | 7.2 |
| 1994 | |
| 1995 | 43.7 |
| 1996 | 38.9 |
| 1997 | 34.7 |
| 1998 | 34.8 |
| 1999 | 32 |
| 2000 | 31.4 |
| 2001 | 2.97333333333333 |
| 2002 | |
| 2003 | 32.8 |
| 2004 | 32.55 |
| 2005 | 34 |
| 2006 | 34.68 |
| 2007 | 40.27 |
| 2008 | 40.26 |
| 2009 | |
| 2010 | 40.66 |
| 2011 | 40.06 |
| 2012 | 38.77 |
| 2013 | 38.32 |
| 2014 | 38.79 |
| 2015 | 38.65 |
| 2016 | 40.7 |
| 2017 | 41.43 |
| 2018 | 41.87 |