Question: what is the period of revolution of mercury in earth years
[{'answer': '88 days', 'provenance': [{'wikipedia_id': '19694', 'title': 'Mercury (planet)', 'start_paragraph_id': 94, 'start_character': 457, 'end_paragraph_id': 94, 'end_character': 464, 'bleu_score': 1.0, 'section': 'Section::::Observation history.:Ground-based telescopic research.\n'}]}, {'provenance': [{'wikipedia_id': '19694', 'title': 'Mercury (planet)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 238, 'bleu_score': 0.845864813470607, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10619249355933673552}, 'section': 'Section::::Abstract.'}]}]