Year % 2012 16.5560578371966 2013 17.7812976878054 2014 20.3563465758394 2015 19.6467562639964 2016 16.8206005734775 2017 15.332517350126 2018 15.9679986098282 2019 17.6617302487441 2020 17.2063027656773 2021 15.1721192540546