Year	% of expense
1987	31.451733973877793
1989	28.27959363957597
1990	65.6579939668175
1991	72.68436121643582
1992	68.01982085000952
1993	66.35664749207032
1994	63.61520558572536
1995	51.972794093214205
1996	52.05641970869894
1997	50.59378771965377
1998	50.680271582446814
1999	52.426392051460624
2000	52.63664683403122
2001	53.60530761482516
2002	53.19606932476185
2003	57.16453687135022
2004	58.1617148239025
2005	59.577342348821084
2006	59.84242642437818
2007	58.23224545721069
2008	59.804507349555536
2009	59.24533677215227
2010	59.722641437043976
2011	58.04572732146421
2012	55.92300249473823
2013	52.89511253668739
2014	50.34105042863003
2015	47.669261965980006
2016	47.49614186506133
2017	45.823116108446754
2018	45.500870482790134
2019	43.53470717192099
2020	40.42344906453431
2021	41.63755831535335
2022	40.21691296103271