Year	% of revenue
1972	14.285714285714285
1973	15.625
1974	18.28793774319066
1975	17.26094003241491
1976	12.131147540983607
1977	11.690788735554808
1978	11.51027819207574
1979	14.087073644178586
1980	16.918016335405458
1981	16.283991632828844
1982	19.169155579690468
1983	14.27372739138542
1984	11.33042950873904
1985	11.3567502346159
1986	11.709120339483556
1987	10.38858880906183
1988	12.474285497400084
1989	12.717755837643002
1990	12.495599216003615
1991	18.46575731423469
1992	18.20003974185076
1993	18.265235665326607
1994	18.338353424104344
1995	17.4139230436421
1996	18.55013109873586
1997	17.75692014866969
1998	18.57111163295782
1999	16.974080958682432
2000	21.777227942709313
2001	20.757527419010653
2002	22.627784274546276
2003	23.46952848403783
2004	26.750486468120656
2005	32.838000889058236
2006	40.86536065001744
2007	39.99405231716283
2008	29.12204439937155
2009	28.086407595076402
2010	27.22311521725124
2011	27.174111137222713
2012	30.360631476845036
2013	28.678827813421186
2014	28.890204315809253
2015	29.829963989189494
2016	33.854491107690414
2017	36.55147830394425
2018	36.6793840750524
2019	33.49881157359334
2020	28.610716405708995
2021	32.18702121261698
2022	36.627235356143714