Year	% of revenue
1972	1.378070701018574
1973	1.1531241619737207
1974	1.2896174863387966
1975	2.1688613477924146
1976	1.847722204523734
1977	2.0171673819742497
1978	2.193645990922842
1979	2.3033648232671773
1980	2.090189451214093
1981	3.2072687737827197
1982	3.2620320855614984
1983	4.286739208418016
1984	4.3864428945073906
1985	4.718601596443358
1986	4.797943738397832
1987	4.519687795945296
1988	4.408732334950431
1989	4.696843689358844
1990	5.218269554483213
1991	5.422477731644127
1992	6.143049745912118
1993	6.794454903303112
1994	7.156284008838178
1995	7.038348219106237
1996	7.1056252484852696
1997	7.124674706836748
1998	6.993020175172525
1999	6.467655184815838
2000	6.37247389567116
2001	6.334423636278561
2002	6.476219365314444
2003	6.279510077755666
2004	6.167896839545964
2005	6.076634735526864
2006	5.713199012373319
2007	5.8574819988620535
2008	6.145693051426002
2009	5.708600552557824
2010	5.7285552219995814
2011	6.069992404526263
2012	5.750086721944865
2013	4.974413748027228
2014	4.720748289379752
2015	4.390476875198997
2016	4.1161591041509755
2017	3.8270752811412985
2018	3.7849660544161763
2019	3.265952123927498
2020	2.8577787037198257
2021	3.1306893701237426
2022	4.219366270991146