| 年度 | 实际值 |
|---|---|
| 1993 | 28.4 |
| 1994 | |
| 1995 | 41.5 |
| 1996 | 42.2 |
| 1997 | 43.3 |
| 1998 | 24.9 |
| 1999 | 25.2 |
| 2000 | 26.6 |
| 2001 | 1.82666666666667 |
| 2002 | |
| 2003 | 27.8 |
| 2004 | 30.18 |
| 2005 | 31 |
| 2006 | 32.67 |
| 2007 | 33.07 |
| 2008 | 37.51 |
| 2009 | |
| 2010 | 38.21 |
| 2011 | 35.11 |
| 2012 | 34.33 |
| 2013 | 34.42 |
| 2014 | 32.44 |
| 2015 | 32.5 |
| 2016 | 32.58 |
| 2017 | 32.97 |
| 2018 | 43.22 |