Year	% of expense
1990	3.2439998353299573
1991	4.349697729697356
1992	6.24197244818294
1993	5.987592862066324
1994	5.92904986355743
1995	10.11121013895662
1996	7.804905867508786
1997	13.154091525988179
1998	18.957461860848316
1999	18.963008678523412
2000	20.411406635430318
2001	18.292816087682812
2002	19.20709211017222
2003	19.621484765446777
2004	19.674342921561816
2005	19.679969811328917
2006	20.144312034946175
2007	18.3317920806834
2008	19.595795074182462
2009	19.343292183743877
2010	19.945355525538773
2011	19.96956881157671
2012	19.081201923582707
2013	19.29308949969179
2014	17.14456878164303
2015	18.54995013912972
2016	18.271163797244803
2017	18.772777487912897
2018	18.229148770171648
2019	19.593067384880822
2020	19.154529171625505
2021	18.370115436793842
2022	15.946248715828448