Year	% of expense
1973	6.708033485093239
1974	6.779513637285871
1975	5.581929721879007
1976	5.100204863276035
1977	5.1797826562613976
1978	5.370327450915467
1979	5.478690179770853
1980	5.214716143355533
1986	4.229601078681069
1987	4.109159155776324
1988	4.973419436618005
1989	4.213667918833135
1990	4.167858082373526
1991	3.7506328092327825
1992	3.5479482814441985
1993	3.849162807709234
1994	3.8152731440433083
1995	3.481700238637845
1996	3.3053699630705133
1997	3.3198573008216723
1998	3.7403518941644913
1999	3.79342765804923
2000	4.014238806000506
2001	4.2182617043238615
2002	4.018857956666891
2003	4.171808507364721
2004	4.166390605620393
2005	4.203381198559722
2006	3.7149550489793635
2007	3.630874556359615
2008	3.6415015070218737
2009	3.4999939440679717
2010	3.487460616324573
2011	3.3176325049518867
2012	3.120313993567207
2013	3.2675397279663487
2014	3.129708490833795
2015	3.3203975113055715
2016	3.3340906621213002
2017	3.4153935654730314
2018	3.4134931117752245
2019	3.3838082786367027
2020	2.912828600693138
2021	2.9572757833099925
2022	3.063605961871587