Year % 2001 20.66057081617605 2002 17.584429695591368 2003 16.17312546324748 2004 18.918996945863817 2005 17.967446787568147 2006 15.540847549917533 2007 21.906601593839735 2008 18.126925677998905 2009 23.552082783906673 2010 22.886864244366752 2011 23.536080618269338 2012 22.042638129365642 2013 21.48841317627184 2014 22.21949333661835 2015 22.857440581540292 2016 20.03914732721094 2017 22.505981704848395 2018 19.151237796601972 2019 16.793334120270586 2020 13.756372719261545 2021 16.767584506756457 2022 15.184679980086061 2023 13.179856737067