{"period":"1936-39","refined":32,"manufactured":16.3}
{"period":"1046-49","refined":31.2,"manufactured":23.1}
{"period":"1956-59","refined":27,"manufactured":23.6}
{"period":"1966-69","refined":21,"manufactured":27.7}
{"period":"1976-79","refined":14.9,"manufactured":34.6}
{"period":"1986-89","refined":8.8,"manufactured":33.9}