Year	% of expense
2001	28.13882780494646
2002	28.690851656178616
2003	27.61621023932838
2004	22.576215084829336
2005	23.382347070969523
2006	21.70345300449231
2007	21.968239976639822
2008	21.31904672995121
2009	20.571765984928618
2010	18.280664719700336
2011	17.290370284426064
2012	19.45783207474403
2013	19.487563599788135
2014	21.235596948906718
2015	20.714889555953146
2016	20.254017657474403
2017	19.833401912265437
2018	20.268251984636475
2019	20.51608996048209
2020	22.57103042502129
2021	24.030830960599516