Question: when did michigan basketball last win the national championship
[{'answer': '1989', 'provenance': [{'wikipedia_id': '14291424', 'title': "Michigan Wolverines men's basketball", 'start_paragraph_id': 43, 'start_character': 23, 'end_paragraph_id': 43, 'end_character': 27, 'bleu_score': 1.0, 'section': 'Section::::History.:Frieder era (1980–89).\n'}]}]