Year	% of expense
1980	16.273003773003772
1981	14.36765681556692
1982	13.873146610466112
1983	13.114853241586927
1984	12.575966041251489
1985	12.928173672159879
1986	12.68532185009916
1987	13.605645000993839
1988	14.215107578730338
1989	11.551828085818846
1990	72.64491104747636
1991	73.45850741377899
1992	73.16671516217103
1993	72.61618307618086
1994	72.32157644399376
1995	69.77550188609052
1996	69.33944243471754
1997	69.86951726737625
1998	70.44552926501677
1999	70.58259118612916
2000	69.86671421196773
2001	70.08441924570856
2002	64.9073605811227
2003	64.3577109038548
2004	64.01656715376171
2005	63.49434886984952
2006	61.44779659070056
2007	61.38326393623852
2008	62.37366736083051
2009	64.40978511861013
2010	65.46178835009191
2011	66.09364576384256
2012	66.55601527784265
2013	66.6841111094287
2014	66.21569526164691
2015	66.18204777579692
2016	66.26085790798115
2017	65.98440113760175
2018	65.3511952498748
2019	64.9501749751632
2020	64.09229132113322
2021	65.05142082356795
2022	64.75315516956783