Question: when did the biltmore house open to the public
[{'answer': 'March 1930', 'provenance': [{'wikipedia_id': '801578', 'title': 'Biltmore Estate', 'start_paragraph_id': 7, 'start_character': 145, 'end_paragraph_id': 7, 'end_character': 155, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '801578', 'title': 'Biltmore Estate', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 871, 'bleu_score': 0.9868845362499331, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7157939574937534597}, 'section': 'Section::::History.\n'}]}]