Question: when did the us try to go metric
[{'answer': '1975', 'provenance': [{'wikipedia_id': '636702', 'title': 'Metrication in the United States', 'start_paragraph_id': 19, 'start_character': 200, 'end_paragraph_id': 19, 'end_character': 204, 'bleu_score': 1.0, 'section': 'Section::::History.:20th century.\n'}]}, {'provenance': [{'wikipedia_id': '636702', 'title': 'Metrication in the United States', 'start_paragraph_id': 19, 'start_character': 0, 'end_paragraph_id': 19, 'end_character': 963, 'bleu_score': 0.9865312178338931, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4827916537685535368}, 'section': 'Section::::History.:20th century.\n'}]}]