Year	% of expense
1972	13.076091989504555
1973	12.764216555297969
1974	12.038670524310211
1975	12.29784501785786
1976	12.137728459530026
1977	11.58410622444473
1978	10.844128708733807
1979	10.275111396838769
1980	9.803072303072303
1981	10.04425856407414
1982	10.09375861067463
1983	9.818164713471669
1984	9.571875443456586
1985	9.473386663651524
1986	9.314404256506236
1987	9.174030104262663
1988	8.648282398323968
1989	8.60262126116993
1990	8.442613194799375
1991	8.304087818464815
1992	8.32740037269311
1993	8.37351184679326
1994	8.293938698364457
1995	9.544794308082425
1996	9.768853594981334
1997	10.057078236152606
1998	10.145014281165382
1999	10.135546035650094
2000	9.823425873904057
2001	9.779084701165267
2002	14.650837679663942
2003	15.236036619197337
2004	15.572236216775273
2005	15.550616933296874
2006	15.38975529192249
2007	15.508364060027935
2008	15.64454666956765
2009	15.40027663157651
2010	15.63637448864886
2011	15.526288358905937
2012	15.661677084130504
2013	15.769176899898552
2014	15.705476677752195
2015	15.530441641831413
2016	15.3465970210003
2017	15.404673748292003
2018	15.57277488488025
2019	15.504947896765376
2020	14.198003872096088
2021	14.976733832258457
2022	14.948820673623263