Year	% of revenue
1975	30.288466668028846
1976	29.64467890191238
1977	29.598403388725913
1978	29.914865481035356
1979	30.265167590305843
1980	29.850123498689534
1981	30.147884687383
1982	30.10522561084361
1983	30.08489776396025
1984	30.33284372742705
1985	29.916427740283982
1986	29.5937052968447
1987	29.665236199612618
1988	30.263586003898038
1989	30.189958994764766
1990	30.965978411237842
1991	25.60816326530612
1992	27.40356937248129
1993	28.387096774193544
1994	32.05093858981228
1995	29.99176850575588
1996	30.50333350842346
1997	30.3567936195975
1998	31.950489347496507
1999	32.27499277863508
2000	32.031967744353295
2001	32.42535361190677
2002	32.628003066962
2003	33.3900947520087
2004	34.65919497989567
2005	35.109670178353966
2006	34.581870923587346
2007	33.83133630711321
2008	33.25308012379439
2009	33.26501892652368
2010	33.852146231490245
2011	34.03206832721595
2012	33.64612075750815
2013	33.527129582623054
2014	32.90340969436081
2015	33.66528969319199
2016	34.14911061391518
2017	33.82787229059621
2018	33.74722059684026
2019	33.706206396740185
2020	31.827867508920576
2021	32.11045712773917
2022	32.43314991794575