Year	% of revenue
1972	1.6532807289465032
1973	1.227524204702628
1974	1.1453235454051116
1975	0.5420918367346939
1976	0.4870865428183053
1977	0.3290326440265619
1978	0.2599952728132216
1979	0.06684699810341076
1980	0.06110825939233947
1981	0.12449255751014886
1982	0.1852489690289789
1983	0.07409694350108058
1984	0.015658093173895486
1985	0.00969324604440998
1986	0.08423096415901092
1987	0.032692384675945076
1988	0.004192771661655307
1990	0.017775934347549142
1991	0.00045757794840351054
1993	0.0004564375958518951
2019	0.003740105417542697
2020	0.03606792040260816
2021	0.6262024970790933
2022	0.6640402979829315