Year	% of revenue
1972	1.4802631578947367
1973	1.729106628242075
1974	0.6607929515418502
1977	1.371696219471395
1978	1.477832512315271
1979	1.262695580565468
1980	0.7807981492192019
1981	1.0886715052066898
1982	2.0365168539325844
1983	1.9300361881785282
1984	1.5374024782010096
1985	1.6078017923036374
1986	1.2647554806070826
1990	2.0218228498074455
1991	2.2900763358778624
1993	2.690780767534186
1994	2.6719056974459727
1995	2.1768251841929
1996	2.158920539730135
1997	1.9813798042492243
1998	2.398843930635838