Year	% of expense
1990	68.63262910798123
1991	65.44989537316903
1992	67.71391609683977
1993	67.69781830022794
1994	64.01214048272873
1995	63.28436396765744
1996	62.371781452794636
1997	67.61421319796955
1998	69.16557515987364
1999	68.3079909414429
2000	67.93006023775254
2001	66.90676676473572
2002	66.64928415663222
2003	68.66180671015049
2004	67.50475234030343
2005	70.78155622079126
2006	74.43382431613111
2007	75.4409231566592
2008	55.138546468003
2009	54.54255039989048
2010	54.89968082960572
2011	17.931792142280994
2014	16.698565104980027
2015	21.61472822714288
2016	19.48283869213187
2017	19.004906041724446
2018	17.392381076964185
2019	17.961422191873588
2020	16.35516704127814
2021	19.437265421552695