Year Cases per 100,000 2000 31 2001 27 2002 26 2003 34 2004 29 2005 31 2006 29 2007 29 2008 27 2009 28 2010 20 2011 18 2012 17 2013 16 2016 11 2017 10 2018 9.8 2019 11 2020 11