Year	% of revenue
1972	21.73516960505868
1973	16.023026545785072
1974	17.15521285927014
1975	16.51265856853211
1976	17.30411505830044
1977	17.566853970618105
1978	18.000193498452013
1979	20.592351750570604
1980	27.23074175193284
1981	28.507120931782254
1982	27.17314602013401
1983	24.063654543605733
1984	25.412770065889145
1985	24.49056974109166
1986	20.212176520435435
1987	16.109582215855788
1988	15.32337942080748
1989	14.190609300573499
1990	16.178320301873267
1991	17.54579774724595
1992	14.583593925899981
1993	15.32132342846683
1994	16.209771157179862
1995	18.230418607434594
1996	20.400295299811336
1997	20.54492796703762
1998	20.29669645059728
1999	21.659907251185633
2000	27.784162715840775
2001	27.350066957387632
2002	29.139942247962576
2003	27.781631883548457
2004	30.79642805888081
2005	32.8754405303442
2006	32.86121218901894
2007	31.082795441733175
2008	32.56391227193426
2009	29.100252937470785
2010	31.201501590862268
2011	32.75913647384955
2012	31.94455501474181
2013	29.17747628525229
2014	25.69826855050578
2015	22.248280483238407
2016	20.725737485545768
2017	21.89199760388549
2018	24.215661303999976
2019	23.400571069854166
2020	19.17793494990543
2021	30.73368451473271
2022	39.89376156201906