Year Cases per 100,000 1953 1.02 1954 1.13 1955 0.79 1956 0.63 1957 1.56 1958 1.14 1959 0.91 1960 0.88 1961 1.05 1962 1.07 1963 0.79 1964 0.9 1965 0.65 1966 1.3 1967 0.79 1968 1.1 1969 1.38 1970 1.05 1971 1.696 1972 1.632 1973 2.208 1974 1.664 1975 2 1976 2.016 1977 1.982 1978 2.478 1979 2.834 1980 2.14 1981 2.616 1982 2.422 1983 2.338 1984 2.544 1985 2.96 1986 2.696 1987 3.302 1988 2.578 1989 3.254 1990 2.89 1991 2.89 1992 2.89 1993 2.89 1994 2.89 1995 2.9 1996 3.02 1997 3.15 1998 3.29 1999 3.44 2000 3.6 2001 3.64 2002 3.68 2003 3.73 2004 3.78 2005 3.83 2006 3.82 2007 3.8 2008 3.78 2009 3.77 2010 3.76 2011 3.74 2012 3.73 2013 3.71 2014 3.7 2015 3.69 2016 3.68