Year % of expense 2011 35.283520617460546 2012 34.96650136237988 2013 30.994070838735738 2014 31.95650092067308 2015 33.39298422226318 2016 35.16645440625711 2017 34.664718465045794 2018 37.316920617245174 2019 36.308934777947066 2020 36.4416280844937 2021 35.63092511436657 2022 47.34049462528346