Year	% of expense
1972	15.86206896551725
1973	15.88571428571432
1974	15.305164319248837
1975	15.606162089752143
1976	14.908503767491913
1977	14.097316962255563
1978	13.513513513513503
1979	13.827534039334328
1980	13.461538461538458
1981	13.9586410635155
1982	13.442575406032464
1983	12.8957528957529
1984	13.050766283524954
1985	12.66124661246609
1986	12.924037460978157
1987	12.874779541446198
1988	12.567501227295036
1989	13.587347232207115
1990	14.068512435476311
1991	14.367816091954047
1992	14.629209844559627
1993	14.051504716274874
1994	13.768525052928707
1995	17.096455443211074
1996	17.112417771011412
1997	17.030372456186225
1998	16.60515709609895
1999	15.82930801572974
2000	15.551955285430626
2001	14.804404283904788
2002	14.639854853597884
2003	14.86330667022482
2004	15.094900357445622
2005	27.00586360157037
2006	27.157757780726495
2007	27.65715950035772
2008	26.652183296343967
2009	24.442580242110758
2010	16.429790454898566
2011	23.77704278420552
2012	24.714549092407488
2013	24.338563192241267
2014	25.405033743106653
2015	24.540791292939414
2016	25.77321912971522
2017	26.560589933821298
2018	26.480959877713563
2019	27.27628887960983
2020	23.823983587073126
2021	24.537079576126253
2022	26.54074876591586