Year Cases per 100,000 2000 19 2001 18 2002 17 2003 14 2004 13 2005 13 2006 10 2007 11 2008 10 2009 9.1 2010 8.3 2011 8.8 2012 6.5 2013 6.7 2014 6.9 2015 6.2 2016 5.7 2017 5.4 2018 4.7 2019 4.7 2020 3.6