Year	% of expense
1972	32.40131578947362
1973	32.021563342318096
1974	31.931311813933235
1975	31.990167676235604
1976	33.71334337133429
1977	34.09161571147275
1978	32.6808279711606
1979	32.433431952662644
1980	33.372258985337936
1981	32.12993102820338
1982	28.448976706373013
1983	26.751283643578823
1984	24.738894851189784
1985	18.79364870206872
1986	17.63460520617812
1987	20.152280774122573
1988	20.446542705449687
1989	20.44763402351085
1990	14.25000467519843
1991	13.334402371051954
1992	12.665384277386634
1993	12.11720529074464
1994	11.251864754269173
2012	6.010705963851628
2013	6.811587452497528
2014	6.853932897040689
2015	7.00807269617993
2016	6.885682513968781
2017	6.7082017350707455
2018	6.55564625570059
2019	6.5839931649065635
2020	5.920484104439438
2021	5.849044341626118
2022	5.915838341493769