Year Cases per 100,000 1990 24.4 1991 37.1 1992 54.8 1993 77.9 1994 105.4 1995 136 1996 169 1997 206.6 1998 253.6 1999 315.7 2000 393.7 2001 478.5 2002 555.1 2003 612.6 2004 650.2 2005 672.5 2006 684.7 2007 690.9