Year	% of revenue
1973	36.50608650608649
1974	37.04918032786889
1975	34.80597893455203
1976	34.3918535115219
1977	34.32254357132403
1978	34.74487116453583
1979	34.81570544042996
1980	34.29712710411584
1981	34.58262675821777
1982	34.60663052776285
1983	33.9038095597682
1984	34.14119251945199
1985	35.26549729099109
1986	37.12905519961636
1987	37.2873916939448
1988	32.80001229432182
1989	33.59837091816767
1991	36.23200360524194
1992	36.855153775474676
1993	36.79870821451879
1994	36.6048808383506
1995	34.01032522468306
1996	34.37401915524115
1997	33.78177708788523
1998	31.31105291599119
1999	32.892094463750695
2000	32.90210729347422
2001	31.88636557670964
2002	32.52786878745561
2003	32.865975824442955
2004	32.2922837422679
2005	32.224904716463215
2006	31.90915305893466
2007	31.68922429991976
2008	32.36919111355257
2009	33.66481780948207
2010	33.90879478827362
2011	33.66104471786508
2012	33.25940463706823
2013	32.9771450152989
2014	32.94156766083397
2015	33.05167390206317
2016	33.31155047850419
2017	32.9329707066514
2018	33.29370927199968
2019	32.85016236196391
2020	33.514799939333585
2021	32.5084275753945
2022	32.37201730143008