Year	% of expense
1984	0.20352064280805626
1985	0.6342179751846255
1986	0.43448391109790746
1987	0.5401856328528367
1988	0.5076007228659509
1994	9.637503587434045
1995	9.333563178762283
1996	2.1457833369694326
1997	9.46527843211156
1998	8.970261518884207
1999	6.92644174787032
2000	7.470945740975135
2001	7.621910101535557
2002	6.944909526112786
2003	7.029731449440847
2004	6.856672195331099
2005	6.297469440589958
2006	6.176124508555643
2007	5.832300979318574
2008	5.527432643883141
2009	6.338182919610634
2010	6.4014020536005996
2011	6.763045573454496
2012	6.993339007251831
2013	6.583968167596245
2014	5.234742956080369
2015	4.825387448998775
2016	4.613348983291821
2017	4.305263157894737
2018	4.037418464096025
2019	3.7340469171110593
2020	3.0104884363891693
2021	2.8247629702650654
2022	3.8114757774449037