Year % 2001 16.484847385444013 2002 16.294942381801395 2003 15.652843220625375 2004 17.342525143171933 2005 16.97184380009191 2006 15.563390364064325 2007 17.369790680122044 2008 15.434347235849943 2009 18.444265678178922 2010 19.58752519920491 2011 16.8960727250315 2012 18.12893408336648 2013 19.68497736804626 2014 19.262494464255383 2015 20.553117984241844 2016 22.029616761257053 2017 21.889413543389903 2018 19.295135770897197 2019 19.7805652631531 2020 23.08371653714093 2021 21.60757034909528 2022 22.83696317854561 2023 20.268949291536345