| 年度 | 实际值 |
|---|---|
| 1992 | 50.81 |
| 1993 | 51.64 |
| 1994 | 52.75 |
| 1995 | 53.57 |
| 1996 | 54.29 |
| 1997 | 21.41 |
| 1998 | 30.15 |
| 1999 | 30.69 |
| 2000 | 31.39 |
| 2001 | 31.97 |
| 2002 | 32.65 |
| 2003 | 32.44 |
| 2004 | 32.92 |
| 2005 | 38.75 |
| 2006 | 33.32 |
| 2007 | 33.82 |
| 2008 | 35.24 |
| 2009 | |
| 2010 | 34.78 |
| 2011 | 36.4 |
| 2012 | 36.8 |
| 2013 | 37.1 |
| 2014 | 37.4 |
| 2015 | 38.11 |
| 2016 | 39 |
| 2017 | 39 |
| 2018 | 40 |