Year	% of expense
1990	15.506399348967967
1991	3.405437985534423
1992	4.583230882714531
2014	36.84408583618808
2015	36.65547847079138
2016	36.71460611727987
2017	33.97362516569294
2018	35.13463063197989
2019	37.543130702936395
2020	40.27686110022538