Year Cases per 100,000 1953 0.74 1954 0.6 1955 0.5 1956 0.99 1957 0.61 1958 0.67 1959 0.91 1960 1.68 1961 1.37 1962 1.66 1963 1.94 1964 2.43 1965 2.43 1966 2.96 1967 2.71 1968 2.73 1969 3 1970 2.52 1971 2.8575 1972 2.545 1973 2.4125 1974 3.36 1975 3.8675 1976 3.525 1977 3.4725 1978 4.11 1979 4.0975 1980 4.575 1981 4.2225 1982 4.7 1983 4.3775 1984 5.095 1985 5.0925 1986 5.12 1987 5.3175 1988 5.125 1989 5.2025 1990 5.11 1991 5.18 1992 5.25 1993 5.32 1994 5.39 1995 5.47 1996 5.49 1997 5.51 1998 5.54 1999 5.57 2000 5.6 2001 5.7 2002 5.81 2003 5.92 2004 6.03 2005 6.15 2006 6.23 2007 6.3 2008 6.37 2009 6.45 2010 6.53 2011 6.54 2012 6.55 2013 6.56 2014 6.57 2015 6.58 2016 6.6