| 年度 | 实际值 |
|---|---|
| 1993 | 30.7 |
| 1994 | |
| 1995 | 37 |
| 1996 | 41 |
| 1997 | 41.8 |
| 1998 | 43 |
| 1999 | 43.3 |
| 2000 | 43.3 |
| 2001 | 2.98 |
| 2002 | |
| 2003 | 35.35 |
| 2004 | 44.17 |
| 2005 | 36 |
| 2006 | 30.72 |
| 2007 | 49.31 |
| 2008 | 31.86 |
| 2009 | |
| 2010 | 32.17 |
| 2011 | 31.35 |
| 2012 | 34.51 |
| 2013 | 37.49 |
| 2014 | 40.17 |
| 2015 | 40.2 |
| 2016 | 41.07 |
| 2017 | 41.23 |
| 2018 | 43.61 |