Year % of expense 2012 2.798296758013944 2013 2.9426352838983774 2014 2.710504276435316 2015 3.1691149892125305 2016 3.3729280180639662 2017 3.1629727149961893 2018 2.97701688425647 2019 2.587733265585606 2020 2.276321201208116 2021 0.879471189827474