Year Cases per 100,000 1990 2.7 1991 2.99 1992 3.31 1993 3.66 1994 4.06 1995 4.5 1996 4.55 1997 4.6 1998 4.66 1999 4.73 2000 4.79 2001 4.72 2002 4.65 2003 4.59 2004 4.53 2005 4.47 2006 4.48 2007 4.49 2008 4.5 2009 4.51 2010 4.53 2011 4.55 2012 4.58 2013 4.61 2014 4.64 2015 4.67 2016 4.71