Year	% of revenue
1973	24.250591016548462
1974	24.26520079942961
1975	21.414852752880922
1976	25.146484375
1977	25.051055139550716
1978	25.538687561214495
1979	25.502315017034967
1980	27.23074175193284
1981	25.46786138327097
1982	25.520750225256876
1983	23.703889024790907
1984	23.350561840846396
1985	25.06710537708892
1986	22.37398408443099
1987	25.41103478838909
1988	26.316473800545996
1989	25.811565661118877
1990	27.32874492215627
1991	30.335161640927183
1992	24.755741973411986
1993	22.251663456443048
1994	20.840491830891022
1995	22.280653272965075
1996	23.32594372824729
1997	23.319664268640096
1998	23.293044680818248
1999	23.45940633742297
2000	25.152471877194472
2001	25.121281602897998
2002	23.78027265264317
2003	24.156525105743654
2004	23.901752456063207
2005	24.369819027018313
2006	25.25546126770865
2007	25.204903961231334
2008	25.14793369393412
2009	22.85401388647519
2010	21.280635061545876
2011	22.958542936123678
2012	20.890152203869135
2013	21.808535421375808
2014	22.36784499075788
2015	22.410846980948573
2016	21.630252548061783
2017	22.95555163104387
2018	24.18215352121993
2019	24.565381123904537
2020	22.804252394891158
2021	26.61310365072506
2022	26.890180769081688