Year	% of expense
1972	31.97881195611047
1973	23.475590649871435
1974	23.188405797101407
1975	23.571691854036064
1976	23.998686802363714
1977	23.376429265376277
1978	22.640396026620373
1979	22.46781637114402
1980	22.213467653431657
1981	22.151186579378045
1982	21.81382341190571
1983	21.46858176587259
1984	21.350627959645845
1985	21.582564765317503
1986	21.404999361861186
1987	20.99968889349785
1988	20.096413105645873
1989	20.47836859157613
1990	10.147853452882849
1991	10.190603806606857
1992	10.065083642650118
1993	9.808559477063264
1994	9.749316013079158
1995	11.10666361695639
1996	10.92900062797881
1997	10.862387583816663
1998	10.764442381644423
1999	10.905304648696786
2000	10.75201029725533
2001	10.418714958941742
2002	10.332831686937345
2003	10.399596254429785
2004	9.831912599033737
2005	10.986628677855112
2006	11.078434604750747
2007	10.997497829848427
2008	10.965659262506382
2009	10.808237617279737
2010	10.99245083015973
2011	10.781735559196266
2012	10.66938424647007
2013	10.463393716758892
2014	10.19999957029565
2015	10.511668044882718
2016	10.718673203403997
2017	10.845785668175381
2018	10.864022422417479
2019	10.885142677349872
2020	10.017481905537052
2021	9.809221205046304
2022	9.60192914285885