Year	% of revenue
1972	59.35761372668193
1973	57.173895220136096
1974	56.782652546646496
1975	55.920172821726155
1976	55.63878351443451
1977	57.011661414990165
1978	57.8606236646902
1979	58.03896688633293
1980	56.55821792335311
1981	54.202160083777486
1982	52.670517426964416
1983	49.911222678013836
1984	49.49465419311727
1985	50.04738138859056
1986	50.0941596705019
1987	52.39717746367414
1988	51.49235899726773
1989	52.48865319382734
1990	51.68391876754132
1991	48.96272210899035
1992	49.10265229777789
1993	49.303565092844046
1994	49.68683653644156
1995	50.4576310344096
1996	52.61976484191416
1997	53.541240751242285
1998	54.58245497575926
1999	54.79479066673699
2000	55.951523815081615
2001	54.08476304260035
2002	50.55263478664337
2003	50.23326919990001
2004	51.64973652106795
2005	53.678086463854555
2006	55.10372975884965
2007	55.42031472242387
2008	54.24354171175516
2009	49.496983456648856
2010	50.213542213021974
2011	53.296036068551395
2012	53.288824626208786
2013	52.156619860913466
2014	53.583224252105055
2015	54.10433208418841
2016	54.19102489980847
2017	52.02085410232051
2018	53.43019419884457
2019	53.27052567012921
2020	54.65236967955155
2021	55.127584846780096
2022	56.40766013937018