Year Cases per 100,000 2000 37 2001 31 2002 33 2003 32 2004 27 2005 24 2006 24 2007 22 2008 23 2009 19 2010 16 2011 14 2012 13 2013 12 2014 12 2015 11 2016 11 2017 8.7 2018 8.8 2019 7.2 2020 4.3