Year	% of revenue
1972	8.280494105490583
1973	9.219398340248963
1974	8.9178901576944
1975	9.234162414965986
1976	9.696420480289987
1977	9.599776656629508
1978	10.883438482936674
1979	11.791499549171409
1980	11.510351739141063
1981	11.484709066305818
1982	10.225929270268006
1983	10.544700745379968
1984	10.952424120056369
1985	10.859418106983611
1986	10.884353741496598
1987	11.533739875368623
1988	10.722115073613091
1989	10.138481979552921
1990	8.924506594377867
1991	7.4896358594686605
1992	7.6026394960962005
1993	8.391605199737091
1994	9.064435922289181
1995	10.058225956761836
1996	10.097711578112897
1997	10.236209688740066
1998	9.706441925187503
1999	8.07984254726699
2000	7.52154602362899
2001	6.634297735507971
2002	6.028668014625889
2003	6.048673831678734
2004	5.954362328986226
2005	6.132122595688873
2006	6.247650094199467
2007	6.776944431663062
2008	6.678547910171961
2009	6.2811266620154695
2010	7.879725543858053
2011	9.934530375821513
2012	8.958312716262224
2013	8.78763601598297
2014	8.472377017835724
2015	7.341009877040919
2016	7.575952299116816
2017	8.197253743483147
2018	7.593808893590872
2019	6.712954923715207
2020	6.065609801457369
2021	8.094371783729457
2022	11.876472451330466