Year	% of revenue
1972	1.1406063321385902
1973	1.0948344958133664
1974	1.0079236475537783
1975	1.0906487745992532
1976	1.046050258506673
1977	1.352191313261289
1978	1.357627055166473
1979	1.2662997182360265
1980	1.5580747018065384
1981	1.21198617187922
1982	1.0366591058138346
1983	2.463682151182151
1984	1.6201184862773548
1985	2.1510213668918676
1986	1.9035416534304694
1987	2.2504815908295592
1988	1.711377296337287
1989	1.9749005901273966
1990	1.8361826002532449
1991	2.170259908384784
1992	2.111035832361656
1993	2.9309676727869336
1994	2.2074648445996954
1995	2.767703616936604
1996	2.607257469611754
1997	2.7641559598420224
1998	3.3589721178218688
1999	3.065764726664381
2000	4.070220658803436
2001	4.616079212853406
2002	4.741169381928924
2003	4.753649877042814
2004	4.54235055130385
2005	4.4871663704918605
2006	4.698596810262208
2007	4.464193419512372
2008	4.590690119762552
2009	4.297943047712267
2010	4.237229432431533
2011	4.359589613340908
2012	4.266558573587092
2013	4.336809949925994
2014	4.144980884969151
2015	4.588365035178916
2016	4.574133265955437
2017	4.4584601492079905
2018	4.632059779350182
2019	4.924424544744276
2020	4.537799792848441
2021	4.2421363161802566
2022	4.532740770041427