Year	% of expense
1974	3.0303030303030303
1975	11.861137897782063
1976	9.26674364896074
1977	10.496089931573803
1978	5.942262602579133
1979	4.214070710678026
1980	3.1150829837680103
1981	1.5063054647361045
1982	1.6658253407370014
1983	4.167649771562171
1984	4.586852416195037
1985	6.937717443208951
1986	6.278963588631435
1987	9.077138196224656
1988	11.261917750221867
1989	9.16445482535301
1990	10.565395576701132
1991	11.563002633579016
1992	7.7965047532607485
1993	6.916529337949593
1994	5.5091021652417185
1995	4.364458118354956
1996	3.254816811126868
1997	2.4685339945081344
1998	3.587314966346331
1999	1.6770541864529702
2000	5.82976045544636
2001	5.729076885070407
2002	5.573933909862137
2003	5.739213067698547
2004	5.101524873775954
2005	4.71826205023761
2006	4.15895061728395
2007	3.6044217296912566
2008	2.557157736373105
2009	2.494161637681455
2010	2.2367608527225946
2011	2.816552292115483
2012	3.0436955045289578
2013	2.9109804785034483
2014	2.6363095886269248
2015	3.0455826968242095
2016	3.4333964553119594
2017	3.525249966020151
2018	4.041086232031617
2019	3.8431811017269015
2020	3.451954473400043
2021	2.77952168112417
2022	4.128638908067722