Year	% of total
1970	4.838361496011819
1971	4.789248210552727
1972	4.628349017943583
1973	5.6396646194760125
1974	5.720248804989192
1975	5.853131664615719
1976	5.869350591419445
1977	5.655490886125938
1978	5.829420698423283
1979	6.015512624601224
1980	5.732171263232166
1981	5.529336021716661
1982	5.551723000170564
1983	5.666446058104945
1984	5.296992201847341
1985	5.326101091314982
1986	5.2755259929140745
1987	5.097537181539231
1988	5.3714998792639355
1989	5.208661457150822