Year	% of revenue
1972	0.8116415329939455
1973	0.4169074548006273
1974	0.21892763865417222
1975	0.029305102751016467
1976	0.03308738378056453
1977	0.0303702128951924
1978	0.02553916004540303
1979	0.023833483396006588
1980	0.018793018393666785
1981	0.017717538148074297
1982	0.02081468684303649
1983	0.01822784810126583
1984	0.01518026565464897
1985	0.010826611811833496
1986	0.010427347456596165
1987	0.008455229559482526