Year	% of expense
1991	36.75869656328584
1992	33.23005256634899
1993	31.003843747206577
1994	33.36062144117594
1995	34.961635801229264
1996	47.88653811819318
1997	38.43377150249964
1998	35.835318269749564
1999	36.894448075140204
2010	46.69460362496034
2011	45.98917868296308
2012	46.53999612435841
2013	45.42750035452903
2014	44.21826454863672
2015	36.40675007283936
2016	41.31831777733927
2017	39.42526787750962
2019	45.54712982829463
2020	43.47038523482469
2021	48.093255467818715