Question: when did michael jordan win first nba championship
[{'answer': '1991', 'provenance': [{'wikipedia_id': '20455', 'title': 'Michael Jordan', 'start_paragraph_id': 2, 'start_character': 570, 'end_paragraph_id': 2, 'end_character': 574, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '20455', 'title': 'Michael Jordan', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1188, 'bleu_score': 0.9094542787656491, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7842156713479557852}, 'section': 'Section::::Abstract.'}]}]