Year	% of revenue
1972	8.620689655172415
1973	10.294117647058822
1974	11.578947368421053
1975	10.44776119402985
1976	11.76470588235294
1977	13.278008298755188
1978	12.732919254658384
1979	12.072892938496583
1980	11.144130757800893
1981	19.336384439359268
1982	27.689243027888445
1983	54.1920216362407
1984	48.622470942746446
1985	59.87925356750823
1986	99.340075419952
1987	114.43697100376534
1988	100.52964881980427
1989	66.08331222511342
1990	52.49702052527036
1991	30.60243862740519
1992	21.867525776166627
1993	16.249579351640662
1994	13.419373071759969
1995	18.860298303540933
1996	18.806716480039963
1997	15.118355024449276
1998	16.54967176893491
1999	18.27816742027925
2000	13.959808541610125
2008	11.879447327279626
2009	13.956710830392712
2010	12.99793220057348
2011	11.61521522310979
2012	11.992079912708519
2013	12.003038170891024
2014	12.549270648024931
2015	11.32945764058407
2016	11.684320698517867
2017	13.61922617908887
2018	14.499616127234935
2019	14.095193427868324
2020	15.447815297274998
2021	15.8259382639258
2022	17.196604828052177