Year Cases per 100,000 1958 2.25 1959 2.4 1960 2.45 1961 2.38 1962 2.25 1963 2.57 1964 3.37 1965 3.18 1966 3.4 1967 3.47 1968 3.68 1969 3.88 1970 3.88 1971 4.3745 1972 4.289 1973 4.5535 1974 4.388 1975 4.5925 1976 4.867 1977 4.5215 1978 4.726 1979 5.0405 1980 4.855 1981 5.3095 1982 5.334 1983 5.2985 1984 5.043 1985 5.1975 1986 5.262 1987 4.9165 1988 5.191 1989 5.3055 1990 5.46 1991 5.44 1992 5.42 1993 5.41 1994 5.39 1995 5.37 1996 5.32 1997 5.28 1998 5.23 1999 5.19 2000 5.15 2001 5.17 2002 5.19 2003 5.22 2004 5.25 2005 5.29 2006 5.31 2007 5.32 2008 5.35 2009 5.37 2010 5.4 2011 5.47 2012 5.55 2013 5.63 2014 5.72 2015 5.8 2016 5.89