Year % of expense 2012 7.603791740461416 2014 7.304560029167933 2015 6.664309360664186 2016 5.757033642759071 2017 4.327078804533065 2018 4.818223152209251 2019 4.211470446056553 2020 6.2324846422394575 2021 6.21144627072076