Year	% of revenue
1975	7.6280041797283165
1976	5.886970172684461
1977	7.407407407407401
1978	8.141674333026646
1979	9.764065335753182
1980	7.85979819437069
1981	7.020511736096442
1982	6.252117926126742
1983	8.789840637450181
1984	7.551945997257686
1985	6.901030392241754
1986	11.769115442278858
1987	13.204270781899119
1988	10.20552090100389
1989	17.62211787791709
1990	16.891610678399445
2010	12.005994220128953
2011	11.655117344580505
2012	15.018015222053094
2013	13.299654934224172
2014	12.830437299798469
2015	11.778300398984754
2016	11.398309290457972
2017	10.514310844049355
2018	10.597964567821423
2019	10.764072315256206
2020	10.37871331023757
2021	13.11878899418796
2022	10.251260880870035