Year Number 1996 0.83064466714859 1998 0.838597416877747 2000 0.309305250644684 2002 0.743997812271118 2003 0.578085064888 2004 0.153857663273811 2005 0.363082945346832 2006 0.354031831026077 2007 0.682846009731293 2008 0.911096274852753 2009 0.938135385513306 2010 1.01733005046844 2011 1.07206296920776 2012 1.04947865009308 2013 0.973354995250702 2014 0.842940807342529 2015 0.862319052219391 2016 0.496157646179199 2017 0.50975513458252 2018 0.480340898036957 2019 0.550631165504456 2020 0.49156528711319 2021 0.4918013215065 2022 0.500283241271973