Year	% of expense
1972	15.057573073516387
1973	14.982021574111068
1974	17.070952092177077
1975	17.270029673590503
1976	16.171456405260596
1978	16.20253164556962
1979	12.41725913214023
1980	12.47454720823063
1981	14.457453481078822
1982	14.009023880268515
1983	13.823697767601603
1984	18.448111984792188
1985	20.41411316713274
1986	16.327243685734253
1987	19.162937615161884
1988	15.392295800051533
1989	17.2406125795603
1990	17.702647461947244
1991	13.790844916672732
1992	16.6836925132114
1993	17.545590369369563
1994	19.18486705068968
1995	16.44972132962983
1996	14.10224045440202
1997	10.80761915378345
1998	14.857793646885003
1999	14.332289067063133
2000	14.013351999907439
2001	14.62821012043524
2002	15.424839829127956
2003	16.1135832356708
2004	13.772232090381674
2005	16.654396409728978
2006	17.799088141720716
2007	19.56183349233013
2008	14.573790116974749
2009	17.24740229587503
2010	18.754209872338507
2011	17.396781588008427
2012	17.415251501658467
2013	16.41968311943263
2014	17.072946151590944
2015	17.64689504259635
2016	16.666497923781005
2017	17.708237814882693
2018	17.11578696334416
2019	18.329976417864522
2020	15.598907931233258
2021	18.801546352867103
2022	16.37594004815474