Year Number 1996 1.45682156085968 1998 1.43966126441956 2000 1.533282995224 2002 1.60834610462189 2003 1.20455622673035 2004 1.19661831855774 2005 1.29527723789215 2006 1.25270569324493 2007 1.14555251598358 2008 1.28543448448181 2009 1.27653253078461 2010 1.33231151103973 2011 1.33797693252563 2012 1.32746982574463 2013 1.3520919084549 2014 1.11995851993561 2015 1.14562010765076 2016 1.18162095546722 2017 1.15070021152496 2018 1.12063598632813 2019 1.14198648929596 2020 1.22151875495911 2021 1.08847510814667 2022 0.860958337783813