Year	% of expense
1983	0.2618943692710607
1984	0.32562683165092804
1988	0.08356213441566193
1989	2.0076377523186033
1990	3.8272634602909834
1991	2.9893493242638502
1992	5.030010989939978
1993	4.905660377358491
1994	13.17205926821893
1995	10.05501993841805
1996	7.85430362329919
1997	7.738620240058289
1998	3.8504672897196257
1999	2.5822459106781843
2000	2.1180509705532815
2001	1.7146383391369509
2002	2.3980089030902274
2003	3.1431099828874354
2004	4.071988551460656
2005	5.683151549166107
2006	4.868253418200164
2007	4.875566339945408
2008	13.918076768016943
2009	12.161242558934084
2010	11.078463174025185
2011	9.6613385654699
2012	9.470246453820048
2013	12.449522402411626
2014	9.626755801427885
2015	8.055000296552132
2016	7.558625333328889
2017	6.7217724002646415
2018	6.276626100786535
2019	5.022874490780631
2020	1.896775562076449