Year % of expense 2013 33.12535722991554 2014 33.83732256034688 2015 27.10228354660746 2016 20.38529352452238 2017 22.856370027205887 2018 24.604065319900034 2019 24.962663099626425 2020 20.51775436461066 2021 23.571767073162768 2022 24.59242535129284