Year	% of revenue
1972	0.329538645895745
1973	0.2681684097613296
1974	0.08743169398907105
1975	0.03872966692486449
1976	0.03185727938834027
1977	0.04291845493562225
1978	0.03782148260211796
1979	0.031843753317057695
1980	0.05336653917993432
1981	0.038828919779451805
1982	0.03342245989304812
1983	0.02989357885926099
1984	0.03269398430688746
1985	0.03031221582297666
1986	0.03331905373887368
1987	0.026346144351736774
1988	0.01881459607677706
1989	0.008118490356817543
1990	0.011184678113193436
1991	0.010078427197558448
1994	0.0065956534643669806
1995	0.004049238743116294
1996	0.001832149459424302
1997	0.006923019572618925
1998	0.006511989772748693
1999	0.003923556049632984
2000	0.0030018595730091743
2001	0.0010565926095875214
2002	0.0007434701020933144
2003	-0.0007327145314876743
2004	-0.0015441500576950612
2005	0.009807741398073383
2006	-0.0323103010073436
2007	-0.012017108438462595
2008	-0.013036499807442524
2009	-0.012093436131696273
2010	-0.012618222964210082
2011	-0.0019387845873468073
2012	-0.013884767690260189
2013	-0.00403853613692763
2014	-0.012106891326038585
2015	-0.012325010527613157
2016	-0.011470148178073543
2017	-0.012398626583631663
2018	-0.012140493229046178
2019	-0.011203300986175316
2020	0.0031020392806230816
2021	0.0038653894683598547
2022	0.0037691269271481736