| 年度 | 实际值 |
|---|---|
| 1993 | 32.1 |
| 1994 | |
| 1995 | 50.4 |
| 1996 | 45.7 |
| 1997 | 40.2 |
| 1998 | 40.6 |
| 1999 | 40.7 |
| 2000 | 37 |
| 2001 | 2.49333333333333 |
| 2002 | |
| 2003 | 29.37 |
| 2004 | 30.56 |
| 2005 | 5 |
| 2006 | 24.21 |
| 2007 | 31.67 |
| 2008 | 32.11 |
| 2009 | |
| 2010 | 34.3 |
| 2011 | 36.26 |
| 2012 | 40.05 |
| 2013 | 39.11 |
| 2014 | 40.54 |
| 2015 | 41.69 |
| 2016 | 41.65 |
| 2017 | 41.44 |
| 2018 | 41.35 |