Year	% of expense
2012	24.536989476747646
2014	25.26209219680626
2015	26.3649307464581
2016	32.904268303134245
2017	36.44819826496142
2018	30.259097357127082
2019	29.674299216758467
2020	25.737147445884606
2021	24.240477024292446