Year	% of expense
1975	18.856718634001485
1976	19.263552676440504
1977	17.020665901262916
1978	17.24986331328595
1979	15.509871768776714
1981	22.25231646471846
1982	20.22666154437188
1983	24.552505966587113
1984	28.15809222046194
1985	28.424913909267858
1986	27.183715537232672
1987	30.076640690410255
1988	23.524362534713454
1989	22.9800629590766
1990	22.35401064888966
1991	21.339538516614056
1992	16.090275063262492
1993	16.928618205631956
1994	17.27373271889401
1995	18.166448801742916
1996	27.10493537585532
1997	26.489531761674918
2002	8.443105652628724
2003	7.485562556413379
2004	7.210016934995671
2005	8.619625870403896
2006	7.161979472401586
2007	7.835916532105994
2008	6.92082254878388
2009	8.04009904811975
2010	8.111127256353456
2011	6.657586731000785
2012	5.636021920522496
2013	4.5327760352940585
2014	3.9297818882633346
2015	4.274499187872225