Year Cases per 100,000 1963 1.06 1964 0.73 1965 4.1 1966 3.77 1967 2.6 1968 3.04 1969 2.19 1970 1.4 1971 2.4675 1972 2.415 1973 2.2725 1974 2.38 1975 2.7875 1976 2.525 1977 2.2725 1978 2.47 1979 2.1375 1980 2.755 1981 2.0825 1982 1.83 1983 1.9775 1984 2.575 1985 1.7625 1986 2.4 1987 2.9775 1988 2.805 1989 2.3725 1990 2.61 1991 2.61 1992 2.6 1993 2.6 1994 2.6 1995 2.6 1996 2.59 1997 2.58 1998 2.58 1999 2.57 2000 2.57 2001 2.6 2002 2.64 2003 2.68 2004 2.73 2005 2.77 2006 2.79 2007 2.81 2008 2.82 2009 2.84 2010 2.86 2011 2.9 2012 2.93 2013 2.97 2014 3.01 2015 3.05 2016 3.09