Year	% of revenue
1972	20
1973	15.789473684210526
1974	19.230769230769234
1975	9.523809523809524
1976	9.67741935483871
1977	6.666666666666667
1978	4.166666666666666
1979	3.606557377049181
1980	3.012912482065997
1981	3.354430379746835
1982	4.562139486103828
1983	4.258774699990977
1984	3.443036226128397
1985	3.5514991240590197
1986	3.635951319071736
1987	3.3719252283294963
1988	3.1019959074727916
1989	2.0061636197076513
1990	1.4331740691986414
1991	1.614159598407478
1992	1.6098053033757547
1993	0.9154214242880395
1994	0.5638123665609518
1995	0.7939006050431925
1996	0.7144476376426884
1997	0.6886110880438463
1998	0.6375349423777671
1999	0.6716474228360123
2000	0.6448355828053445
2001	0.6073121563826479
2002	0.6052790259464786
2003	0.6194685773203552
2004	0.6926537838009326
2005	0.7260047592174893
2006	0.7093523556985768
2007	0.7937271279591566
2008	0.8632770881863803
2009	0.9004128091630511
2010	0.9128559798590276
2011	0.9243918963133093
2012	0.7776268804057084
2013	0.6504145637500774
2014	0.7429116383761929
2015	0.7267539245044177
2016	0.8000914665052766
2017	0.6795817597110603
2018	0.6293892336317012
2019	0.6594939516833379
2020	0.6424378797405073
2021	0.6870587422910299
2022	0.48891847277040174