Year	% of expense
1972	18.562769041553192
1973	17.515386726253478
1974	16.697426989469115
1975	14.908858135706883
1976	13.947574864067953
1977	13.538348444008822
1978	13.277445464855129
1979	12.677019633086578
1980	11.53983748147391
1981	11.26879741104167
1982	11.173980189583556
1983	10.75350565973982
1984	10.880273160377902
1985	10.470192067847343
1986	10.37050133584787
1987	10.704684082214749
1988	10.670698485343793
1989	10.423870655304542
1990	10.283689241700563
1991	10.135312915842267
1992	10.027601587210274
1993	9.68826152803031
1994	9.527575788337792
1995	9.22324092370358
1996	8.965185723286123
1997	8.922748233859842
1998	8.840499165327222
1999	8.939264630386795
2000	9.51413992979499
2001	9.77634715225716
2002	10.554762000937252
2003	10.854252769710165
2004	10.92365440816197
2005	10.747832509589525
2006	10.918355507119925
2007	10.850614373408504
2008	10.704068289695616
2009	10.861508806721002
2010	10.612193199105395
2011	10.97621987703608
2012	10.883737122774981
2013	11.021818165573476
2014	10.72746540797686
2015	10.2284256778126
2016	10.05068642152165
2017	10.226570004087986
2018	10.159228911445904
2019	9.863809082333926
2020	7.041765192279262
2021	7.901038216812516
2022	9.163260874385259