Year	% of expense
1990	9.275682368672152
1991	7.355204452297919
1992	7.05992873464532
1993	6.866244198887052
1994	7.3633823809596075
1995	17.60950072613296
1996	29.284329648451823
1997	19.85732658912547
1998	21.218615519557055
1999	20.981871795448413
2000	22.45651903200365
2001	21.951164138256996
2002	40.53068859354806
2003	34.0893107171579
2004	34.17955126895391
2005	24.334507346018672
2006	36.97313203256926
2007	36.349027701536116
2008	36.908099350489664
2009	32.65814198442211
2010	31.647235226508986
2011	31.817824322063625
2012	32.59447441412772
2013	31.91857520382851
2014	35.175965997151124
2015	33.79859732709892
2016	36.51055838401635
2017	36.589018854892146
2018	34.978824919965156
2019	34.10482683987552
2020	39.1265700031972
2021	31.50550589998774
2022	33.90858951771906