Year	% of expense
1990	1.3311773775053586
1991	1.6551939924906132
1992	1.7935774889915153
1993	2.091999613040534
1994	2.5486523898705316
1995	3.103629668595476
1996	3.9822872782065875
1997	3.0139813676011142
1998	16.217133738609864
1999	15.849580025989576
2000	15.077584090931277
2001	15.227077478032832
2002	15.418555014283092
2003	20.497947669228875
2004	22.531536074896895
2005	21.11257056211136
2006	19.905959641548858
2007	14.129076990189212
2008	15.362361630499914
2009	17.16916026993586
2010	14.8113178606542
2011	14.594067100108665
2012	13.415710826528052
2013	8.579817348053432
2014	8.316263100952332
2015	7.747549686266055
2016	7.673173570299133
2017	8.082205044428665
2018	7.509627926770375
2019	6.59596080275542
2020	6.152020956782649
2021	5.7771531633808815
2022	5.6881203318813975