| 年度 | 实际值 |
|---|---|
| 1993 | 23.6 |
| 1994 | |
| 1995 | 20.6 |
| 1996 | 32.7 |
| 1997 | 32.8 |
| 1998 | 27.9 |
| 1999 | 28.8 |
| 2000 | 27 |
| 2001 | 2.08666666666667 |
| 2002 | |
| 2003 | 32.66 |
| 2004 | 32.31 |
| 2005 | 33 |
| 2006 | 32.24 |
| 2007 | 34.39 |
| 2008 | 35.96 |
| 2009 | |
| 2010 | 38.21 |
| 2011 | 40 |
| 2012 | 38.46 |
| 2013 | 38.22 |
| 2014 | 55.8 |
| 2015 | 40.03 |
| 2016 | 40.08 |
| 2017 | 39.02 |
| 2018 | 40.03 |