Year	% of revenue
1972	58.325079784307256
1973	59.00319884428852
1974	61.35640251367012
1975	64.57273652085452
1976	62.87065575512807
1977	63.219119178020186
1978	63.34200636021971
1979	60.451099317664905
1980	60.82460732984293
1981	62.18489727928929
1982	63.268670266137896
1983	61.20291245204046
1984	58.86124952849854
1985	59.791860563499455
1986	59.420486393635294
1987	60.64444652081637
1988	61.76544857689117
1989	64.31340677202886
1990	65.05724341599579
1991	66.3138838601866
1992	65.61709832159247
1993	65.71130477476372
1994	64.04240746278735
1995	64.68739604671113
1996	66.04259265180828
1997	67.19919155291687
1998	67.14142893350981
1999	65.50501008419502
2000	66.71540841115507
2001	65.0272682201289
2002	62.37870863131999
2003	62.72654565523435
2004	63.29596002681128
2005	65.00655203272821
2006	65.23156216396603
2007	65.69018175753385
2008	66.28276017941103
2009	64.95107543560312
2010	61.28528086788636
2011	63.34552527013761
2012	65.51730988641718
2013	64.20095955479206
2014	63.658400961442375
2015	64.89343285454432
2016	64.23154156765568
2017	64.11057281276717
2018	65.1641514705453
2019	65.86195766722534
2020	64.5163696610642
2021	64.47203512192262
2022	67.8574414850167