Year Cases per 100,000 2000 2.5 2001 2 2003 1 2004 0.66 2005 0.78 2006 1.1 2007 0.88 2008 1 2009 0.88 2010 0.76 2011 0.77 2012 0.75 2014 0.97 2015 0.91 2016 0.78 2017 0.61 2018 0.62 2019 0.42 2020 0.51