Year Cases per 100,000 1990 197.6 1991 238.4 1992 271.3 1993 304.4 1994 335.3 1995 366.4 1996 392.5 1997 425.1 1998 460.2 1999 498.4 2000 540.6 2001 579.7 2002 612.1 2003 628.5 2004 623 2005 601.5 2006 570.6 2007 539.1