| 年度 | 实际值 |
|---|---|
| 1992 | 35.3 |
| 1993 | |
| 1994 | |
| 1995 | 36 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 20.3997 |
| 2000 | 20.8984 |
| 2001 | 36.8469 |
| 2002 | 36.7545 |
| 2003 | 36.8446 |
| 2004 | 37.0946 |
| 2005 | 37.1984 |
| 2006 | 37.2288 |
| 2007 | 37.3553 |
| 2008 | 37.1161 |
| 2009 | 38.3768 |
| 2010 | 39.0501 |
| 2011 | 38.9227 |
| 2012 | 38.6831 |
| 2013 | 38.3903 |
| 2014 | 31.1615 |
| 2015 | 32.2016 |