Year Cases per 100,000 2000 25 2001 20 2002 24 2003 21 2004 26 2005 29 2006 27 2007 23 2008 23 2009 20 2010 23 2011 20 2012 23 2013 21 2014 20 2015 20 2016 19 2017 20 2018 21 2019 21 2020 15