| 年度 | 实际值 |
|---|---|
| 1993 | 21.1 |
| 1994 | |
| 1995 | 27.9 |
| 1996 | 29.7 |
| 1997 | 30.3 |
| 1998 | 31.9 |
| 1999 | 31.8 |
| 2000 | 31.6 |
| 2001 | 2.08666666666667 |
| 2002 | |
| 2003 | 33.03 |
| 2004 | 38.35 |
| 2005 | 39 |
| 2006 | 39.18 |
| 2007 | 39.26 |
| 2008 | 40.55 |
| 2009 | |
| 2010 | 46.2 |
| 2011 | 32.46 |
| 2012 | 32.84 |
| 2013 | 36.34 |
| 2014 | 43.9 |
| 2015 | 44.84 |
| 2016 | 43.68 |
| 2017 | 43.52 |
| 2018 | 42.5 |