Year	% of total
1970	12.990142948456352
1971	12.718790279615721
1972	14.47648747087427
1973	14.391452055508843
1974	11.885013296651847
1975	13.161360551242252
1976	11.998779395881265
1977	12.090302950622617
1978	11.893442466792994
1979	11.859920218997361
1980	10.808321952951584
1981	14.327869506802472
1982	13.912683993302222
1983	12.146485977497305
1984	27.167635940442565
1985	24.9353328448588
1986	24.288168935845075
1987	24.73832181646379
1988	25.302432608954167
1989	26.54271022075314