Year	% of revenue
1972	2.9402661714639375
1973	2.5809734995819564
1974	2.09079525931103
1975	1.8595845112430989
1976	1.7874298992336397
1977	1.8407457989430547
1978	1.918520761707971
1979	2.003680580637389
1980	1.837531467161101
1981	1.8715428444678546
1982	0.9227133303162908
1983	0.9369497081722858
1984	1.1580261949240898
1985	1.2890643580839996
1986	1.2740419641556162
1987	1.41095950511122
1988	1.0611022892682282
1989	0.8057211313697984
1990	0.5436310807010952
1991	0.377636659154216
1992	0.24841829527680517
1993	0.42378532161749616
1994	0.3947229841423926
1995	1.0029978410794411
1996	0.8255602639099635
1997	0.7302603805701102
1998	0.7982119372733317
1999	0.8300025212669287
2000	0.650534966643206
2001	0.5805885641727365
2002	0.5140030554412713
2003	0.46241085412716343
2004	0.3669530997446547
2005	0.3555955455533616
2006	0.39534002624902276
2007	0.5003603060689537
2008	0.6637768094091777
2009	0.799512853851652
2010	0.9857005240757775
2011	1.1860086501293632
2012	1.1285806769744584
2013	1.2183199695235725
2014	0.989840069926538
2015	0.9311825129995257
2016	0.9244955741759044
2017	0.9141997949032701
2018	0.8209298699659159
2019	0.7718113602435356
2020	0.5441133264017757
2021	0.37806276523341387
2022	0.3738452235239261