Question: how many times have we been to the bottom of the mariana trench
[{'answer': 'Four', 'provenance': [{'wikipedia_id': '19036', 'title': 'Mariana Trench', 'start_paragraph_id': 18, 'start_character': 247, 'end_paragraph_id': 18, 'end_character': 251, 'bleu_score': 1.0, 'section': 'Section::::Research history.\n'}]}, {'provenance': [{'wikipedia_id': '19036', 'title': 'Mariana Trench', 'start_paragraph_id': 21, 'start_character': 0, 'end_paragraph_id': 21, 'end_character': 557, 'bleu_score': 0.9317067856825251, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7258976751475107445}, 'section': 'Section::::Research history.:Descents.\n'}]}]