Year	% of revenue
1973	23.096942094990244
1974	23.526121367810184
1975	26.707212974818606
1976	25.507009663808354
1977	25.694664553618612
1978	25.74941250644802
1979	26.820649630253623
1980	25.820960948369564
1981	25.61526596277828
1982	24.33468018345441
1983	23.73097435941044
1984	23.83177570093458
1985	24.712880190897515
1986	24.598145570656627
1987	25.30859162538506
1988	25.224690313538602
1989	29.105615256912447
1990	23.83521877624582
1991	25.47067853295013
1992	26.62398029921375
1993	28.484603892775542
1994	31.956834973481712
1995	30.451310622102064
1996	29.52891795836664
1997	30.561280342266038
1998	29.733529817350977
1999	31.02408968356231
2000	30.26788533802486
2001	31.609098045696815
2002	32.35269045443819
2003	32.33506394833481
2004	31.715337776628594
2005	31.726116283100268
2006	30.694281608280225
2007	30.17894884188069
2008	30.90677228200115
2009	32.7885019964145
2010	32.470034801036995
2011	32.30286620672748
2012	31.695194346712373
2013	31.265731043561168
2014	30.955585458713983
2015	30.49346117249877
2016	31.54749031068644
2017	31.571913080144135
2018	31.367690479055394
2019	31.49507147442008
2020	32.32417275533603
2021	31.660755054457773
2022	31.2683425396894