Question: what percentage is within 3 standard deviations of the mean
[{'answer': '99.73 %', 'provenance': [{'wikipedia_id': '9606881', 'title': '68–95–99.7 rule', 'start_paragraph_id': 2, 'start_character': 153, 'end_paragraph_id': 2, 'end_character': 162, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]