Year Cases per 100,000 1968 6.54 1969 6.55 1970 6.56 1971 6.37 1972 6.87 1973 5.83 1974 5.96 1975 5.29 1976 6.59 1977 6.01 1978 5.94 1979 5.47 1980 6.51 1981 6.17 1982 6.48 1983 6.68 1984 7.25 1985 7.22 1986 6.37 1987 6.62 1988 7.54 1989 7.29 1990 7.4 1991 7.46 1992 7.52 1993 7.59 1994 7.66 1995 7.73 1996 7.77 1997 7.82 1998 7.86 1999 7.91 2000 7.96 2001 7.99 2002 8.02 2003 8.05 2004 8.09 2005 8.13 2006 8.21 2007 8.28 2008 8.36 2009 8.44 2010 8.53 2011 8.56 2012 8.59 2013 8.63 2014 8.67 2015 8.71 2016 8.75