Year	% of revenue
1973	29.15038616214244
1974	26.994203164372646
1975	27.261667234415278
1976	27.9296875
1977	27.244825686629337
1978	25.64135197541863
1979	26.066842900302117
1980	26.355153788932366
1981	26.78812600686137
1982	27.024169198087744
1983	27.884534328699104
1984	27.75384079750046
1985	29.781752046074573
1986	29.573040125660395
1987	29.378003507413396
1988	30.07142857142857
1989	29.726948220362722
1990	28.39991770470942
1991	25.221229612606876
1992	27.40356937248129
1993	28.387096774193544
1994	30.12935929858441
1995	30.259657297459793
1996	29.87946778797906
1997	30.964869044696368
1998	30.85239210488663
1999	32.75383715021961
2000	31.23550123138223
2001	28.935174350573366
2002	30.716312601377183
2003	30.31420024082901
2004	29.777264167458753
2005	29.49237105083178
2006	31.25523368002039
2007	29.238231084835302
2008	30.12898506575119
2009	28.835935923304895
2010	28.545681476160606
2011	29.864481840324025
2012	30.028506900556064
2013	29.89764660404968
2014	30.136254133422852
2015	29.631175028052304
2016	29.561879182913955
2017	29.30890081434176
2018	28.752999930448564
2019	28.31138511909179
2020	29.029092689697883
2021	29.110313799242277
2022	27.070426596345328