Year	% of expense
1990	19.435215946843854
1991	19.99534450651769
1992	18.58216970998926
1993	19.47975748093096
1994	17.82065834279228
1995	12.77464514874587
1996	14.271711429131543
1997	13.151593295266162
1998	10.903538710256871
1999	12.49791423327215
2000	7.519905632556768
2001	15.979528006823998
2002	16.933747907199233
2003	15.467832892162503
2004	15.213532421426335
2005	25.29844644317253
2006	25.905666037303032
2007	25.955097421466366
2008	25.286703830796903
2009	18.627491243612386
2010	17.544735835423133
2011	14.323136432343903
2012	14.934205636897019
2013	14.792497678009367
2014	15.102423219182763
2015	14.556718870562104
2016	14.34628397044109
2017	13.45901347150306
2018	14.296290044812384
2019	13.501402188437813
2020	11.5190426598766