Year % of people at risk 2003 0.4 2004 0.2 2005 0.2 2006 0.2 2007 0.2 2008 0.3 2009 0.4 2010 0.2 2011 0.3 2012 0.7 2013 1.5 2014 1.2 2015 0.7 2016 0.4 2017 0.3 2018 0.4 2019 0.2 2020 0.1 2021 0.1 2022 0.3