Year Cases per 100,000 1990 4.42 1991 5.51 1992 6.88 1993 8.6 1994 10.75 1995 13.47 1996 15.02 1997 16.75 1998 18.69 1999 20.86 2000 23.29 2001 20.82 2002 18.61 2003 16.65 2004 14.89 2005 13.32 2006 14.14 2007 15 2008 15.92 2009 16.89 2010 17.94 2011 17.88 2012 17.82 2013 17.77 2014 17.72 2015 17.67 2016 17.64