Year	% of revenue
1972	11.351667641895844
1973	8.973128598848362
1974	11.231633961147818
1975	9.599809433063365
1976	9.18380977825274
1977	9.551047875408559
1978	8.086354746502185
1979	8.037565173691776
1980	8.159821452872826
1981	10.84748222318965
1982	12.902515660335801
1983	9.356944420772756
1984	11.154974740599561
1985	9.46649274838244
1986	8.338189948396257
1987	6.56448183750977
1988	7.315414799583854
1989	6.317063163677583
1990	6.993187282067151
1991	7.98964903768397
1992	7.86391082943132
1993	10.800730666096781
1994	8.157817253901273
2012	17.35687441639473
2013	11.320275334556893
2014	10.466713878708566
2015	9.538143016403886
2016	8.776009985306432
2017	8.243187272350742
2018	8.968292336129673
2019	9.392165444797024
2020	9.532443684784932
2021	9.709785360764405
2022	11.621585711615506