Year	% of revenue
1972	14.285714285714285
1973	15.625
1974	29.18287937743191
1975	28.363047001620746
1976	26.35561160151324
1977	24.86256030517222
1978	26.917839310031777
1979	26.13001624212653
1980	23.229169570429015
1981	20.632459702227145
1982	22.343198479500405
1983	21.233451426440425
1984	20.494017753763025
1985	23.45890870089824
1986	20.82289764089552
1987	20.90740643627528
1988	23.410634986905528
1989	22.27801285065037
1990	21.015517033004567
1991	17.788413041772678
1992	17.353653514417942
1993	15.14604730388088
1994	15.578587144543226
1995	17.13793247826269
1996	15.285583672729198
1997	16.52600492475165
1998	16.327761826855586
1999	18.081108735274448
2000	16.138038979812926
2001	17.029365966410523
2002	13.41475267774289
2003	14.329962933154988
2004	16.255477393356916
2005	15.291801613005651
2006	15.009221873286476
2007	17.045403569699957
2008	18.034489112776956
2009	16.13537916321438
2010	12.695624408965916
2011	10.558004739158907
2012	7.8306663340746745
2013	10.03471072307959
2014	10.610301381182266
2015	10.325061587020015
2016	9.333115849381175
2017	10.464204600647378
2018	10.437237116347287
2019	11.474947300812326
2020	11.048893438286036
2021	13.733162150117687
2022	14.43909022997838