Year	% of expense
1972	6.509707458490732
1973	6.1468501313261985
1974	8.323381464191366
1975	7.4833871852709875
1976	7.76368112099981
1977	8.194070080862534
1978	7.6226901781147856
1979	9.46853878339234
1980	10.446159349925896
1981	11.648827991627451
1982	12.895409521780806
1983	12.909999275939468
1984	14.255557221792845
1985	15.817535545023699
1986	15.195269526952696
1987	15.055359087273674
1988	15.276415676873341
1989	15.360957001214942
1990	20.20762481664073
1991	19.371617344374364
1992	18.458162168401866
1993	17.697128181592703
1994	17.839579520706437
1995	19.416371192096555
1996	19.695813827280844
1997	19.48594374890583
1998	19.12183290191775
1999	17.967799056467655
2000	17.41692637620179
2001	17.868081601694293
2002	15.515648814439073
2003	14.011085584335671
2004	13.454410634310207
2005	12.772291058829651
2006	12.923170951753137
2007	12.72064301031571
2008	11.182752527903576
2009	9.462542562303447
2010	9.31183425888474
2011	9.938382471971511
2012	9.706748005436442
2013	9.587766196449827
2014	9.36750251759135
2015	8.750044403218057
2016	8.56884074654197
2017	8.424866019047842
2018	9.045915745987879
2019	9.03460071021026
2020	5.696152915335432
2021	6.145724725416708
2022	8.776843618807568