Year	% of revenue
1982	84.62620578778134
1984	82.37762237762237
1985	85.5220945876022
1986	84.42512769961466
1988	86.60800454158388
1989	85.55182699478001
1990	83.63469416584263
1991	83.71407090393846
1992	82.67891070297657
1993	83.32027606789778
1994	83.32726007884187
1995	81.76972281449893
1996	80.85844500374124
1997	81.06889189071418
1998	74.45976561155254
1999	81.47573611192414
2000	74.61415988289977
2001	77.73793805388769
2002	72.5366800245722
2003	61.3196555095073
2004	76.41033191318844
2005	70.78190565825363
2006	72.37113490945897
2007	76.56984923729514
2008	74.47512720960088
2009	72.23949273345544
2010	64.21574482894678
2011	58.75937264259877
2012	56.23512455320425
2013	50.43354954957972
2014	57.33439469777279
2015	47.7267665808912
2016	52.53039066887551
2017	48.766834804303876
2018	47.163885257940095
2019	39.81884720454944
2020	58.69569770620661