Question: when did tobacco companies start putting warning labels on cigarettes
[{'answer': '1966', 'provenance': [{'wikipedia_id': '15978610', 'title': 'History of warning labels in the US', 'start_paragraph_id': 2, 'start_character': 3, 'end_paragraph_id': 2, 'end_character': 7, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '15978610', 'title': 'History of warning labels in the US', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 593, 'bleu_score': 0.9788329837059241, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13186546462159975817}, 'section': 'Section::::Abstract.'}]}]