Year	% of expense
1972	39.872851424534964
1973	38.06178714404411
1974	35.24172587073298
1975	30.044229149115413
1976	32.63432654234963
1977	37.34825760473497
1978	42.33320757089857
1979	40.80950612699591
1980	41.4159674598652
1981	39.47231575806658
1982	37.406540016873706
1983	34.988728463313834
1984	38.18345045351825
1985	36.36388922885212
1986	34.15043108577363
1987	32.901407287332354
1988	32.736525334572946
1989	30.50581983261258
1990	30.48531533248047
1991	31.938989174615774
1992	35.35320345894954
1993	35.32667744149968
1994	39.881573354970826
1995	33.422701583178295
1996	34.60253029882505
1997	30.98249870039854
1998	23.235434392889132
1999	18.554017945820796
2000	26.851361585803605
2001	27.77405029050285
2002	19.205914991144198
2003	27.478455340740975
2004	21.25610133052998
2005	21.70755579055823
2006	20.878583617274295
2007	26.533337469310663
2008	27.000422730841233
2009	30.83477544068159
2010	32.2330696507527
2011	25.247318012312814
2012	25.186819030272684
2013	24.752371935831242
2014	25.234533071085934
2015	25.536080785737536
2016	26.307499076934988
2017	24.660774278114776
2018	26.196197476828765
2019	24.665769876835224
2020	21.182670155988433
2021	20.496551364210582
2022	23.837941367881353