| 年度 | 实际值 |
|---|---|
| 1978 | .68 |
| 1979 | .7 |
| 1980 | .74 |
| 1981 | .75 |
| 1982 | .73 |
| 1983 | .73 |
| 1984 | .72 |
| 1985 | .77 |
| 1986 | .79 |
| 1987 | .77 |
| 1988 | .79 |
| 1989 | .84 |
| 1990 | .88 |
| 1991 | .91 |
| 1992 | .92 |
| 1993 | .95 |
| 1994 | 1.04 |
| 1995 | 1.07 |
| 1996 | 1.07 |
| 1997 | .96 |
| 1998 | .9 |
| 1999 | .81 |
| 2000 | .7 |
| 2001 | .73 |
| 2002 | .69 |
| 2003 | .68 |
| 2004 | .7 |
| 2005 | .69 |
| 2006 | .73 |
| 2007 | .78 |
| 2008 | .79 |
| 2009 | .79 |
| 2010 | .78 |
| 2011 | .68 |
| 2012 | .67 |
| 2013 | .66 |
| 2014 | .61 |
| 2015 | .69 |