Year	% of expense
1972	4.90185896770174
1973	4.753191109524237
1974	4.7697306988383845
1975	4.956694756554312
1976	4.438113801634304
1977	3.833203255658381
1978	4.158921933085515
1979	4.2624249971697195
1980	4.435202072715508
1981	4.3468362499430935
1982	5.140672456972355
1983	4.163675520459444
1984	4.332961205693554
1985	4.537205081669688
1986	4.545850292754055
1987	4.5217898206962985
1988	4.439473216207847
1989	4.710014409221895
1990	4.6665373423860315
1991	4.595302455216474
1992	4.503455047785166
1993	3.6543805968054475
1994	4.128790831839083
1995	6.888265584587554
1996	7.804242724359516
1997	7.646009500317155
1998	7.27953707103761
1999	7.052369220785826
2000	7.85127182946331
2001	7.781889505508799
2002	8.213570782432747
2003	8.27416561085284
2004	7.9386949127963415
2005	8.061361477045937
2006	7.768903309473521
2007	7.431116618003964
2008	7.670662044398593
2009	7.9169799212859
2010	7.756618485489394
2011	7.510357341787389
2012	7.596623348046011
2013	7.182944594703962
2014	7.068350940273237
2015	7.591718907055112
2016	7.86881619087932
2017	7.617165395254622
2018	7.473605198003104
2019	7.666780977199833
2020	7.403748309815013
2021	7.745371969355433
2022	7.954748086992663