Year Cases per 100,000 1953 0.64 1954 0.72 1955 0.77 1956 0.55 1957 1.01 1958 0.76 1959 0.85 1960 1 1961 1.24 1962 0.9 1963 0.78 1964 1.02 1965 0.76 1966 1.12 1967 1.7 1968 1.33 1969 0.85 1970 1.54 1971 2.239 1972 2.118 1973 1.607 1974 1.826 1975 2.315 1976 1.894 1977 1.693 1978 2.092 1979 1.691 1980 2.03 1981 1.899 1982 2.688 1983 2.167 1984 2.516 1985 2.955 1986 2.534 1987 2.423 1988 2.252 1989 1.911 1990 2.35 1991 2.4 1992 2.45 1993 2.51 1994 2.56 1995 2.62 1996 2.71 1997 2.81 1998 2.92 1999 3.03 2000 3.14 2001 3.23 2002 3.31 2003 3.4 2004 3.49 2005 3.59 2006 3.71 2007 3.83 2008 3.96 2009 4.1 2010 4.24 2011 4.32 2012 4.41 2013 4.49 2014 4.58 2015 4.68 2016 4.78