Year	% of total
1970	5.492012262778544
1971	5.409428410407363
1972	4.150370431017502
1973	4.792246717020085
1974	3.7951694963242306
1975	4.570684813955454
1976	3.557375708990259
1977	3.492059918244069
1978	3.3169971042679527
1979	4.698225159801436
1980	5.058475662550207
1981	4.863599832360136
1982	4.985230586525597
1983	4.554880821448906
1984	4.332823461522791
1985	5.211858610686761
1986	5.386648328890955
1987	5.313488548510314
1988	11.615735354985315
1989	10.953333755747941