Year	% of expense
1972	44.91725768321513
1973	48.4744094488189
1974	49.50090744101633
1975	46.8785046728972
1976	45.169867060561295
2003	50.58453870014672
2004	52.51140264855129
2005	49.376024789293744
2006	49.66659158839249
2007	48.73274577181445
2008	50.441053933125566
2009	53.83100098047955
2010	55.666435571431926
2011	50.42856239270611
2012	48.1898837123575
2013	49.982667102401756
2014	44.18491533600531
2015	45.719777198190265
2020	48.592981770146984