| 年度 | 实际值 |
|---|---|
| 1993 | 26.9 |
| 1994 | |
| 1995 | 17.6 |
| 1996 | 17.2 |
| 1997 | 17.3 |
| 1998 | 19.6 |
| 1999 | 34.4 |
| 2000 | 25.9 |
| 2001 | 1.74666666666667 |
| 2002 | |
| 2003 | 25.3 |
| 2004 | 36.11 |
| 2005 | 28 |
| 2006 | 26.22 |
| 2007 | 25.07 |
| 2008 | 35.36 |
| 2009 | |
| 2010 | 33.65 |
| 2011 | 34.36 |
| 2012 | 37.33 |
| 2013 | 32.56 |
| 2014 | 32.56 |
| 2015 | 32.43 |
| 2016 | 34.05 |
| 2017 | 36.2 |
| 2018 | 38.39 |