Year	% of expense
1988	0.6923719708726274
1989	0.9929078014184398
1990	4.207209711796868
1991	4.582475610847579
1992	3.871840392256319
1993	6.4937106918239
1994	10.257030541276082
1995	15.082529907627077
1996	4.5138358049227945
1997	4.9583924531196075
1998	6.945794392523365
1999	11.60632236721191
2000	6.755579030767199
2001	13.371093577819899
2002	6.086153805358427
2003	6.919356924912227
2004	8.421538738556867
2005	3.9001327830632
2006	3.4464452247119435
2007	3.3496133039541562
2008	2.915627069412445
2009	2.3966071474914483
2010	4.297461078806361
2011	4.76534386625008
2012	4.927946620535472
2013	5.504392003865162
2014	4.7816405492804535
2015	7.144766248699874
2016	8.556596984904525
2017	10.720107190178405
2018	16.075549045640518
2019	8.948152964538625
2020	15.876681509032062