Year	% of expense
1986	3.251217978940751
1987	3.6009905855825473
1988	2.8685845047401113
1989	2.9235095708617598
1990	51.801104071488055
1991	53.10554868844952
1992	56.71369042057469
1993	58.222283372938136
1994	58.721125216680406
1995	58.4847999521033
1996	58.5345529739687
1997	59.09991390169679
1998	59.27078892046972
1999	60.2643505324439
2000	59.98543151527139
2001	58.35342703104665
2002	59.399798786256824
2003	60.38856190623757
2004	60.40582855314546
2005	61.51489689113723
2006	61.29054273994022
2007	61.73053131616245
2008	60.836364798312836
2009	63.65155336315063
2010	65.06034069325574
2011	64.13774310803662
2012	64.8102272287645
2013	65.93596899980238
2014	66.77240924408059
2015	68.1909173300042
2016	68.75909670850947
2017	68.4720940689133
2018	68.08165490000906
2019	68.29281733863152
2020	75.50490577281076
2021	71.11674608150162
2022	69.01796108491804