Year Cases per 100,000 1963 1.33 1964 2.54 1965 3.13 1966 4.37 1967 3.41 1968 3.51 1969 3.3 1970 3.57 1971 3.447 1972 3.494 1973 3.651 1974 2.978 1975 4.805 1976 4.672 1977 4.629 1978 3.866 1979 3.753 1980 3.18 1981 3.227 1982 3.904 1983 4.361 1984 3.808 1985 4.495 1986 5.312 1987 4.449 1988 5.486 1989 4.993 1990 5.45 1991 5.56 1992 5.68 1993 5.81 1994 5.94 1995 6.07 1996 6.32 1997 6.58 1998 6.86 1999 7.15 2000 7.45 2001 7.62 2002 7.8 2003 7.98 2004 8.17 2005 8.37 2006 8.49 2007 8.61 2008 8.74 2009 8.87 2010 9.02 2011 9.08 2012 9.15 2013 9.23 2014 9.3 2015 9.38 2016 9.47