Year Cases per 100,000 2000 14 2001 13 2002 11 2003 11 2004 10 2005 9.5 2006 9.1 2007 7.6 2008 7.7 2009 6 2010 5.9 2011 5.4 2012 5.3 2013 4.4 2014 4.5 2015 4.8 2016 4.8 2017 4.7 2018 4.1 2019 4.3 2020 3.4