Year Cases per 100,000 2000 31 2001 30 2002 28 2003 28 2004 26 2005 23 2006 21 2007 21 2008 18 2009 19 2010 17 2011 17 2012 15 2013 14 2014 19 2015 16 2016 18 2017 16 2018 16 2019 15 2020 15