Year	% of expense
1972	3.571428571428571
1973	3.7958115183246073
1974	2.470007057163021
1975	2.3241954707985695
1976	4.554554554554555
1977	5.272181740248607
1978	8.436724565756824
1979	9.837608849140974
1980	6.515028432168968
1981	6.243272335844995
1982	8.409596834034133
1983	12.119675456389452
1984	13.619351894112278
1985	12.522236831928224
1986	16.804206042859043
1987	23.145340610470992
1988	27.579079235828374
1989	24.894100630230394
1990	20.219435736677116
1991	17.848200312989047
1992	17.696907961752046
1993	17.962613752838514
1994	19.82234566607274
1995	16.153881009560923
1996	11.643624635343999
1997	13.339268692991876
1998	24.357541028947175
1999	23.895042238148537
2002	28.337166506912286
2003	19.9615883893901
2004	16.148800787877946
2008	9.677544081790918
2009	10.885607099992804
2010	9.189038572107352
2011	7.925647366766098
2012	7.472141896060839
2013	7.701264546371242
2014	7.919117521178438
2015	9.326257067894089
2016	9.90662792164312
2017	11.140531207273774
2018	11.730459867006054
2019	11.989104054806342
2020	12.296277770020403
2021	12.975589412052308
2022	12.475228037612814