Year % of expense 2010 5.4220043249666725 2012 6.230101336357809 2013 6.14895075720793 2014 5.362281250304993 2015 6.492823304773957 2016 7.418696414435145 2017 7.073307545607317 2018 9.063054394845466 2019 7.904858527615163 2020 8.480182723175723 2021 9.79886060915679