Year Cases per 100,000 1990 12.2 1991 18.6 1992 27.4 1993 38.9 1994 52.7 1995 68 1996 84.5 1997 103.3 1998 126.8 1999 157.8 2000 196.8 2001 239.3 2002 277.6 2003 306.3 2004 325.1 2005 336.3 2006 342.3 2007 345.4