Year	% of expense
1974	16.697426989469115
1975	15.421521590130228
1976	15.585654330408241
1977	15.692509663773599
1978	15.389064817609423
1979	14.767211009387752
1980	13.935323421152294
1981	13.546672123573623
1982	13.102470215213781
1983	13.02448844798687
1984	12.529089317309605
1985	12.523176197497701
1986	12.556914192828916
1987	13.770861743667469
1988	13.887633163229374
1989	12.784436280987368
1990	10.207593141085866
1991	10.008553632946857
1992	10.065083642650118
1993	9.808559477063264
1994	9.45582630043334
1995	9.83531293168479
1996	10.05578759170837
1997	10.472066449404885
1998	10.611138702436367
1999	11.314590131263609
2000	10.90152719288184
2001	11.601512105233553
2002	13.73457292524157
2003	12.172623649278535
2004	13.287339489567701
2005	13.141048721138514
2006	12.917980064799764
2007	12.790648597021269
2008	12.65298052534578
2009	12.281746226984257
2010	12.042954049573318
2011	11.64950267108372
2012	11.490100155356494
2013	11.987187574039144
2014	11.705844578041411
2015	11.978766474119203
2016	12.404457173259246
2017	13.220644269110245
2018	13.71603581019149
2019	13.727138396046614
2020	12.672146047124738
2021	12.479110552720577
2022	12.124144878247465