Question: when did sir alex ferguson leave manchester united
[{'answer': '2013', 'provenance': [{'wikipedia_id': '43223', 'title': 'Alex Ferguson', 'start_paragraph_id': 1, 'start_character': 147, 'end_paragraph_id': 1, 'end_character': 151, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '43223', 'title': 'Alex Ferguson', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 214, 'bleu_score': 0.5862368042766161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3577157478868297163}, 'section': 'Section::::Abstract.'}]}]