Year	% of expense
1972	17.746710526315766
1973	19.016172506738528
1974	18.378437126399383
1975	18.453164779211665
1976	17.47329174732921
1977	15.706290807337556
1978	15.892704860841958
1979	9.439718934911252
1980	8.68301544050863
1981	8.142314083449062
1982	7.997242939450716
1983	7.915423413053029
1984	7.919535115043322
1985	7.12983704484561
1986	7.660106818072472
1987	9.0173936956447
1988	7.968599280073405
1989	8.692911422218218
1990	5.708105547278721
1991	5.625718835707346
1992	5.72925312216221
1993	6.116505273892399
1994	5.658018651709755
2012	2.454814534920335
2013	2.5815042426866057
2014	2.61719913483781
2015	2.791493071564494
2016	2.7432352658530226
2017	2.6028762944811135
2018	2.5009205921660826
2019	2.5348460613767547
2020	2.067456819146505
2021	2.1490520984232737
2022	2.598375554718588