Year	% of expense
1972	3.303834808259587
1973	3.9740470397404706
1974	3.837638376383764
1975	6.924964936886395
1976	6.192493062655177
1977	6.576284904896802
1978	8.107603213151505
1979	8.453999112652765
1980	6.545483966665768
1981	7.188655561963565
1982	8.084099541312966
1983	9.228680401800553
1984	11.515908324747286
1985	11.547152128281006
1986	9.87511533029284
1987	7.6051357446637
1988	9.11056700602986
1989	9.507875742987645
1990	10.249910302016268
1991	10.37005628247643
1992	10.161029629957003
1993	10.730493844496761
1994	11.013420815402561
1995	11.839147185305364
1996	10.703063762155342
1997	10.687309367967929
1998	10.649721090474076
1999	10.38151558558823
2000	9.44463868568267
2001	9.15093418905364
2002	7.6799619732409745
2003	6.738252752566256
2004	6.249923185577013
2005	15.240243623239042
2006	17.49951164748156
2007	18.41080023697951
2008	22.020107905449912
2009	28.445199746639144
2010	20.648344127108416
2011	22.057396543594994
2012	23.276237060697948
2013	22.650073882402708
2014	19.07052051797424
2015	20.139114865534793
2016	16.01090442089975
2017	17.056880760814657
2018	14.919352812647963
2019	12.886185183275419
2020	9.71887669807215
2021	10.18809000079227
2022	15.488639299015844