Year Cases per 100,000 1990 21.19 1991 9.251 1992 29.25 1993 245.6 1994 468.7 1995 456.3 1996 223.3 1997 60.66 1998 40.84 1999 16.99 2000 7.425 2001 4.925 2002 3.62 2003 1.29 2004 0.5645 2005 0.1679 2006 0.08419