Year % of expense 2010 5.491915638591464 2012 5.456640329012609 2013 4.719162864364274 2014 5.182190261202458 2015 6.023342792650759 2016 6.585428973984973 2017 7.677912114128898 2018 9.063054394845466 2019 8.038446477337894 2020 8.798754545555772 2021 10.22511123696571