Year % 2010 15.6595837833882 2011 17.6242756564352 2012 19.7833135448908 2013 18.8619597811953 2014 20.2987213486134 2015 20.5476496154599 2016 21.675010733536 2017 24.7994876766213 2018 24.3461226673481 2019 22.5117313115603 2020 23.658144647537