Year	% of expense
1990	6.122837041262597
1991	5.889931897662434
1992	7.4706510138740665
1993	9.443413729128016
1994	9.776186213070726
1995	12.004701141705842
1996	13.643952041280924
1997	13.292472329597107
1998	11.450150107883635
1999	18.415774221998234
2000	25.40369297610427
2001	23.771626297577857
2002	23.539612008236695
2003	23.313313313313312
2004	24.738934903363077
2005	26.723781425499883
2006	20.397904646577764
2007	23.710615362151387
2008	23.616860869720384
2009	20.35990476625884
2010	7.830253687787368
2011	9.470265048232827
2012	7.259481917370138
2013	7.6803145636135675
2014	9.432769051652564
2015	19.505591871415486
2016	24.74088119191193
2017	23.440561498255548
2018	22.485731760233442
2019	23.93240831755876
2020	23.304550379561487
2021	29.835354852051665
2022	25.478797828341687