Question: when did man utd last win premier league
[{'answer': '22 April 2013', 'provenance': [{'wikipedia_id': '19961', 'title': 'Manchester United F.C.', 'start_paragraph_id': 21, 'start_character': 325, 'end_paragraph_id': 21, 'end_character': 338, 'bleu_score': 1.0, 'section': 'Section::::History.:Ferguson years (1986–2013).\n'}]}, {'provenance': [{'wikipedia_id': '19961', 'title': 'Manchester United F.C.', 'start_paragraph_id': 21, 'start_character': 0, 'end_paragraph_id': 21, 'end_character': 338, 'bleu_score': 0.6930977286178771, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3177393232372731360}, 'section': 'Section::::History.:Ferguson years (1986–2013).\n'}]}]