Year	% of expense
1991	8.253059099192917
1995	19.672895728160242
1996	19.238569539350575
1997	19.483061989028037
1998	19.378543586692818
1999	21.24084542593269
2000	21.88508088242189
2001	17.90003747895051
2002	18.398827063089048
2003	18.52830914923836
2004	18.23718991566374
2005	18.042203417234003
2006	17.251072654265865
2007	17.83715413052175
2008	17.679279673778886
2009	16.22990608286309
2010	16.311303868343835
2011	16.495865713579803
2012	16.390485263253613
2013	16.555773286875453
2014	17.142303710502237
2015	16.76712781084406
2016	16.671327050712133
2017	16.696961949578174
2018	16.251377977483113
2019	16.296168174520442
2020	15.39670233783582
2021	15.62672745000741
2022	15.809752088251553