Question: when did capitol reef become a national park
[{'answer': 'December 18 , 1971', 'provenance': [{'wikipedia_id': '447433', 'title': 'Capitol Reef National Park', 'start_paragraph_id': 35, 'start_character': 511, 'end_paragraph_id': 35, 'end_character': 529, 'bleu_score': 1.0, 'section': 'Section::::History.:National park status.\n'}]}]