Question: when did the last survivor of titanic die
[{'answer': '31 May 2009', 'provenance': [{'wikipedia_id': '7680815', 'title': 'Millvina Dean', 'start_paragraph_id': 1, 'start_character': 48, 'end_paragraph_id': 1, 'end_character': 59, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7680815', 'title': 'Millvina Dean', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 241, 'bleu_score': 0.73445076342173, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1717081461168529629}, 'section': 'Section::::Abstract.'}]}]