Year	% of revenue
1972	54.8103186646434
1973	57.3715651135006
1974	59.85529917872506
1975	59.16833667334669
1976	58.1646423751687
1977	56.57323332017371
1978	53.0259044216168
1979	53.520995912300265
1980	55.854979858313655
1981	53.38031682674317
1982	52.37772800666701
1983	52.96956881493059
1984	52.31925662914557
1985	52.85985934623163
1986	52.139377250582505
1987	51.52492804753505
1988	49.56615247700979
1989	46.8086867739176
1990	50.41070568479152
1991	52.42310734726164
1992	52.108172616836114
1993	48.01207091663523
1994	49.73794280836535
1995	49.66919676612575
1996	51.26296712939499
1997	52.7305272564294
1998	54.0567797540076
1999	51.87022629744897
2000	51.7062693419138
2001	52.42067205898575
2002	53.08238178182053
2003	50.66379509721746
2004	48.94755449022523
2005	48.758249465527584
2006	50.511082166425524
2007	51.81370919797962
2008	54.454922531421246
2009	51.11331048715337
2010	48.523668657766414
2011	49.21098955306453
2012	48.203809566027246
2013	47.76484341051293
2014	46.9461414430563
2015	46.19196729857041
2016	47.95876144034575
2017	48.377942102078315
2018	48.484762178310895
2019	47.4790211471673
2020	46.36663745277937
2021	48.76878126877071
2022	49.03079843237007