Question: when's the last time the kansas city chiefs won a superbowl
[{'answer': 'January 11 , 1970', 'provenance': [{'wikipedia_id': '20297793', 'title': 'Kansas City Chiefs', 'start_paragraph_id': 2, 'start_character': 270, 'end_paragraph_id': 2, 'end_character': 287, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '20297793', 'title': 'Kansas City Chiefs', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 671, 'bleu_score': 0.95223003536211, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14534480488057265189}, 'section': 'Section::::Abstract.'}]}]