Year	% of expense
1972	2.6973684210526288
1973	3.032345013477085
1974	2.3584393000760833
1975	2.0454744974102335
1976	1.8140101814010194
1977	1.9121152451031278
1978	1.9807737033878632
1979	2.037105522682442
1980	0.9653561697158407
1981	0.9469395187908309
1982	1.4633629069315326
1983	4.0167820305045145
1984	5.994293641860576
1985	9.288663416348214
1986	10.39022277823222
1987	9.262314805266234
1988	9.322970991193055
1989	8.967227536904524
1990	9.336059493457846
1991	10.1798195169424
1992	10.240887387343355
1993	11.471634193662725
1994	12.459892156781082
2012	6.140940865293784
2013	8.340434159586389
2014	8.577019755650138
2015	7.844682331441601
2016	7.306599305336281
2017	6.947037384263324
2018	6.696503294818676
2019	6.200512632007709
2020	4.858022877417529
2021	4.893910075660219
2022	5.849108356395435