Year Measure 1971 0.01281 1972 0.0128 1973 0.0124 1974 0.01343 1975 0.01421 1976 0.01338 1977 0.01266 1978 0.01262 1979 0.01272 1980 0.01288 1981 0.01659 1982 0.01816 1983 0.01809 1984 0.01833 1985 0.01952 1986 0.0193 1987 0.01889 1988 0.01924 1989 0.01935 1990 0.01875 1991 0.01833 1992 0.01803 1993 0.0182 1994 0.01701 1995 0.01698 1996 0.01726 1997 0.01817 1998 0.01789 1999 0.01871 2000 0.01888 2001 0.01862 2002 0.01667 2003 0.01807 2004 0.01964 2005 0.01848 2006 0.01865 2007 0.01803 2008 0.0194 2009 0.01801 2010 0.01869