Year	% of total
1970	4.885119018229429
1971	5.028823609200303
1972	5.039834590168144
1973	5.074204212686059
1974	5.116573243780316
1975	5.155443630134908
1976	5.1774079437182206
1977	5.090097663115743
1978	5.117715551163998
1979	5.121461347876442
1980	5.130248223351453
1981	4.8037683245796625
1982	4.596559108280804
1983	4.3149959016754655
1984	4.0556282150004375
1985	3.788783570803829
1986	3.5186182112009945
1987	3.258715685010955
1988	3.0018232791577626
1989	2.758027368865516