Year	% of expense
1975	2.439848677816293
1976	3.1434774210978373
1978	4.083373797063626
1979	4.8302105118309475
1980	5.9711794817128006
1981	4.92998923952689
1982	5.051051859111918
1983	6.2125312687834215
1984	6.9549104385423
1985	7.942510001462184
1986	8.768128021336866
1987	8.59721215051166
1988	8.768250383157218
1989	9.102125934134236
1990	9.70687216262785
1991	9.44460457689377
1992	9.572967433664443
1993	8.936457234390893
1994	9.464858073050607
1995	7.977165759191901
1996	7.958875536892659
1997	9.651277441540929
1998	9.141626758401182
1999	7.847983644917897
2000	7.570082099627758
2001	7.333555184524851
2002	6.55706429184751
2003	5.767505878701395
2004	5.4316953625738345
2005	4.911018026972474
2006	4.572148219033389
2007	4.385314837759285
2008	4.027843192993311
2009	4.545520052046229
2010	4.6068070101830525
2011	5.173470556554928
2012	5.777536577835267
2013	5.446249074329694
2014	5.234742956080369
2015	4.825387448998775
2016	4.528591016908115
2017	4.096380980067511
2018	3.581890258134204
2019	3.2504941336928486
2020	2.7569684374819747
2021	2.724053326004487
2022	3.0694809203500752