Year	% of expense
1973	19.337539432176655
1974	15.242191883299046
1975	16.298150465860104
1976	10.299607542835263
1977	10.09308408339103
1978	9.120921802175038
1979	9.178616617460987
1980	10.68608444843728
1981	10.922283750238686
1982	8.161320010518013
1983	8.327268316351285
1984	9.251164663254155
1985	9.681488489435509
1986	9.62751427861932
1987	9.799221516064478
1988	10.311318421145623
1989	12.67727617191729
1990	10.525401069518717
1991	10.931125653510714
1992	12.285948123898262
1993	14.127045407299619
1994	12.708793268629984
1995	12.182725782943278
1996	12.12840897655228
1997	11.886723354581765
1998	11.262046339963092
1999	11.342553550345757
2000	11.575523480382191
2001	12.523308940975447
2002	12.910473258627055
2003	12.69445568088102
2004	11.94746737295695
2005	12.404691930108278
2006	13.28431563666053
2007	11.854101391956444
2008	11.214105557603741
2009	11.341809919667087
2010	11.899013822995459
2011	12.132331139180454
2012	12.01010952924002
2013	11.405970673526685
2014	11.389193432837187
2015	10.671558127941399
2016	10.995412842881612
2017	12.188605100113982
2018	13.27181774827982
2019	13.238472554317479
2020	12.637239646250897
2021	9.42693993148321
2022	9.925190275209578