Year Cases per 100,000 2000 30 2001 29 2002 27 2003 27 2004 22 2005 18 2006 17 2007 15 2008 14 2009 13 2010 15 2011 13 2012 12 2013 11 2014 8.1 2015 8.8 2016 7.6 2017 6.7 2018 6.2 2019 5.5 2020 4