Year Number 1996 0.808773279190063 1998 0.735702812671661 2000 0.773133337497711 2002 0.114022798836231 2003 0.18930858373642 2004 0.115224100649357 2005 0.150281816720963 2006 0.196952044963837 2007 0.311637252569199 2008 0.641149759292603 2009 0.269764304161072 2010 0.315519511699677 2011 0.277477234601974 2012 0.321495771408081 2013 0.30405580997467 2014 0.261683821678162 2015 0.270181685686111 2016 0.280886232852936 2017 0.261637181043625 2018 0.307371318340302 2019 0.327528208494186 2020 0.284111678600311 2021 0.236004292964935 2022 0.215328231453896