Year	% of expense
1998	18.880631676730143
1999	20.061373225930186
2001	3.4573838266510384
2002	19.096828441408103
2003	8.136899762499679
2004	15.19151814372704
2005	17.99560020939701
2006	18.50165056852916
2007	25.20043110231864
2008	25.387014276934135
2009	20.03492295633375
2010	19.198026659388336
2011	10.781192543216573
2012	16.19822887496552
2013	19.47755323177773
2014	18.23493693486889
2015	22.983577499390346
2016	9.775273931858495
2017	13.754040681946284
2018	11.887310537901135
2019	9.815496302418065
2020	11.826283747049832
2021	12.594249513316624