Year	% of revenue
1973	9.976247030878877
1974	10.195634988374593
1975	9.778287219074917
1976	10.067788099422538
1977	9.977566166528469
1978	10.296604588456848
1979	10.710769981467573
1980	10.43113250391635
1981	10.84748222318965
1982	12.740528943388549
1983	11.22199037090823
1984	11.978801169590625
1985	11.869581631285612
1986	11.674507291931398
1987	11.27647930376283
1988	10.20552090100389
1990	11.011165104844888
1991	10.455953047602442
1992	11.362159281190884
1993	10.518475569268864
1994	9.347819552164752
1997	9.93342062093377
1998	8.737229717431868
1999	9.54291141773015
2001	9.349383180927132
2002	9.457804073458476
2003	10.767642433658827
2004	9.002226437443866
2005	9.73105570032946
2006	9.571883937560758
2007	9.989651157776724
2008	9.820240489917722
2009	10.481426742449576
2010	12.695624408965916
2011	10.673125530313733
2012	10.830313153680533
2013	11.5267152023692
2014	11.150544608182528
2015	11.237960571505631
2016	10.131609308214955
2017	10.48066341406203
2018	10.370109015703378
2019	11.005047522780888
2020	10.420020407753256
2021	9.745576334752283
2022	10.21280187957213