Year % 2000 0.35284821110604586 2001 0.3536479801479379 2002 0.35493112059419824 2003 0.3470765170608458 2004 0.3416169868482037 2005 0.329248551810164 2006 0.32544597624161303 2007 0.3295981742828302 2008 0.3221252792431255 2009 0.32209179116810027 2010 0.32031179036908153 2011 0.3126685017642594 2012 0.31316684403171274 2013 0.31159518226250066 2014 0.3130191162133422 2015 0.3102378097189967 2016 0.2969024866286388 2017 0.2916135158901237 2018 0.2902882379007027 2019 0.2871840922939298 2020 0.2765854100510906