Year	% of expense
2000	0.4495504495504496
2001	8.828649145193749
2002	11.991334682884421
2003	6.50252037029315
2006	18.805471000072412
2007	17.530427954456222
2008	14.324979267002961
2009	14.96849308776075
2010	16.229570280601678
2011	19.456775171133295
2012	18.13970298979766
2013	22.792656748924863
2014	14.515092306596799
2015	23.175765227573986
2016	23.446658851113718
2017	21.68653105116946
2018	21.859264140376123
2019	23.354531279980183
2020	20.303898201250323