Year % 2001 17.73585139381575 2002 16.698017151954822 2003 17.221107517259476 2004 18.149058109559057 2005 16.560715960955665 2006 15.291111288539659 2007 19.62784901801109 2008 17.672641173896494 2009 21.469619280569074 2010 21.7736478352896 2011 17.151870252919526 2012 18.79059205730637 2013 21.241867662922107 2014 20.34376259705592 2015 22.830923579519716 2016 21.773553504917313 2017 20.75505543688363 2018 19.151237796601972 2019 19.8778887135407 2020 23.592363863833484 2021 23.815853218774745 2022 23.77646541633809 2023 21.28730854957611