Year	% of revenue
1973	31.5625
1974	31.712062256809336
1975	31.07779578606159
1976	36.79949558638083
1977	37.070571075956465
1978	36.20971402632773
1979	33.51424157192093
1980	34.61098876592423
1981	39.48812599975391
1982	42.73961444474613
1983	39.34598172664553
1984	40.28413372296043
1985	39.96514278053358
1986	43.626480592346304
1987	43.471078714143374
1988	42.30234941359547
1989	40.26766964425639
1990	43.486051485231755
1991	43.82824671321774
1992	44.94572933495757
1993	45.73767060504796
1994	46.30862005441265
1995	45.442840993147335
1996	46.340645141790645
1997	46.299482710195
1998	46.5183382267274
1999	46.94778290458321
2000	47.08562731890472
2001	46.89099794423445
2002	49.15025337397139
2003	49.04404568932618
2004	45.257471581455846
2005	41.27135327363942
2006	34.365186182144456
2007	34.34201873218468
2008	39.07812296592596
2009	45.83743027602114
2010	45.05875642379969
2011	43.968688692942436
2012	43.27938426071671
2013	48.86353389977458
2014	49.22281915862419
2015	48.530180177946704
2016	49.69777271217093
2017	50.132394387178735
2018	46.897062378017914
2019	44.42317880009246
2020	49.18370214260393
2021	46.63026904606925
2022	41.057021946186644