Year	% of expense
1990	60.2697148728487
1995	53.79692094793288
1996	51.4118191637093
1997	45.734744707347446
1998	56.94422746445868
1999	57.47426640036872
2009	54.51778179626281
2010	51.82905439840094
2011	51.79798523186484
2012	53.375917620729886
2013	53.762284067079946
2014	49.70083999874865
2015	46.43347783106062
2016	42.06684785423977
2017	39.004641406353954
2018	48.746769903579626
2019	47.7347158354104
2020	43.31586285675889
2021	48.17737716276419