| 年度 | 实际值 |
|---|---|
| 1993 | 32.3 |
| 1994 | |
| 1995 | 13.8 |
| 1996 | 19.2 |
| 1997 | 25.7 |
| 1998 | 29.3 |
| 1999 | 29.9 |
| 2000 | 29.3 |
| 2001 | 1.72 |
| 2002 | |
| 2003 | 27.44 |
| 2004 | 26.7 |
| 2005 | 35 |
| 2006 | 31.91 |
| 2007 | 28.49 |
| 2008 | 28.41 |
| 2009 | |
| 2010 | 29.31 |
| 2011 | 31.78 |
| 2012 | 36.28 |
| 2013 | 36.6 |
| 2014 | 40.78 |
| 2015 | 41.23 |
| 2016 | 40.59 |
| 2017 | 38.3 |
| 2018 | 38.32 |