Question: when was the first metal roller coaster built
[{'answer': '1959', 'provenance': [{'wikipedia_id': '15632708', 'title': 'History of the roller coaster', 'start_paragraph_id': 15, 'start_character': 3, 'end_paragraph_id': 15, 'end_character': 7, 'bleu_score': 1.0, 'section': 'Section::::History.:The rise of steel.\n'}]}, {'provenance': [{'wikipedia_id': '15632708', 'title': 'History of the roller coaster', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 577, 'bleu_score': 0.977897140678983, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7372437624470745817}, 'section': 'Section::::History.:The rise of steel.\n'}]}]