Year	% of expense
1980	9.272873624899388
1981	9.996006921336347
1982	8.362814107006082
1983	8.741863010542072
1984	9.189340813464227
1985	7.433773191784901
1986	4.971078261729374
1987	3.8518366509337114
1988	5.089343847211172
1989	5.262139366866112
1990	28.278286244860002
1991	27.85996237134319
1992	29.788967210087876
1993	34.19383681277554
1994	35.54547624731438
1995	29.74415169850874
1996	30.314891371272758
1997	29.624150339864048
1998	29.002143696839777
1999	28.62286817899113
2000	30.426132145508532
2001	30.367224044303455
2002	30.715912466580853
2003	30.99437226720224
2004	33.5895418507535
2005	33.18624411947047
2006	31.924995286495378
2007	30.426155003280574
2008	31.038607312187455
2009	31.4124200762877
2010	33.503421541869386
2011	33.82020496332764
2012	33.26410565718621
2013	33.77505990807548
2014	29.847162850617792
2015	40.535997959174395
2016	43.00712862262937
2017	41.85181450942921
2018	39.048777056734565
2019	40.04017534384837
2020	48.7383435168737
2021	49.41048667294011
2022	46.184254392692466