Year Cases per 100,000 2000 11 2001 9.2 2002 7.5 2003 7.3 2004 6.6 2005 7.3 2006 6.3 2007 6.5 2008 6 2009 5.3 2010 6 2011 6.4 2012 6.1 2013 5.9 2014 5.2 2015 5.6 2016 5.1 2017 4.4 2018 4.7 2019 4.5 2020 3.6