Year	% of revenue
1972	1.5873015873015872
1973	1.8518518518518516
1974	0.8163265306122449
1975	1.3201320132013201
1976	1.643835616438356
1977	1.366742596810934
1978	1.2173913043478262
1979	1.5822784810126582
1980	1.6260162601626018
1981	1.1776251226692835
1982	0.8220786846741044
1983	0.7826396300249021
1984	1.5667949422759757
1985	1.6581321628871006
1986	1.466275659824047
1987	3.0251141552511416
1988	1.459188326493388
1989	1.2300595810109551
1990	1.1681855840927922
1991	0.9291164164410535
1992	1.0523044134623925
1993	1.0363813019540105
1994	1.1005855483000706
1995	1.2096396817969115
1996	2.032140799745734
1997	1.0088991752778955
1998	0.4474968567063691
1999	0.2723950836009301
2000	0.2912593081620567
2001	0.33239984377207343
2002	0.5341272273543191
2004	1.9808440559676506
2005	1.9780127316925904
2006	2.0105459482808357
2007	2.199642869233701
2008	2.340424790048395
2009	2.6088807280697233
2010	2.8991277519009717
2011	2.50529315770616
2012	3.1420808840798267
2013	3.4845272776481195
2014	3.488276969000588
2015	3.262088745348829
2016	3.0630799721168014
2017	3.2325461540546025
2018	2.990783349401766
2019	3.0008125155573078
2020	2.228664055545521
2021	2.8489611617613786
2022	3.7316874678149072