Question: when did canada convert from imperial to metric
[{'answer': '1970', 'provenance': [{'wikipedia_id': '2732123', 'title': 'Metrication in Canada', 'start_paragraph_id': 1, 'start_character': 31, 'end_paragraph_id': 1, 'end_character': 35, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2732123', 'title': 'Metrication in Canada', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 1316, 'bleu_score': 0.990171692033262, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13441870544757566891}, 'section': 'Section::::Conversion process.\n'}]}]