Year 1 in: rate varies by country 2000 36 2001 35 2002 34 2003 34 2004 33 2005 34 2006 34 2007 37 2008 36 2009 31 2010 30 2011 29 2012 29 2013 30 2014 29 2015 30 2016 31 2017 32 2018 35 2019 37 2020 36