Question: when did myanmar became a member of asean
[{'answer': '23 July 1997', 'provenance': [{'wikipedia_id': '106539', 'title': 'Association of Southeast Asian Nations', 'start_paragraph_id': 8, 'start_character': 146, 'end_paragraph_id': 8, 'end_character': 158, 'bleu_score': 1.0, 'section': 'Section::::History.:Expansion.\n'}]}, {'provenance': [{'wikipedia_id': '106539', 'title': 'Association of Southeast Asian Nations', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 348, 'bleu_score': 0.660295830564348, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17114880017777102743}, 'section': 'Section::::History.:Expansion.\n'}]}]