Question: when did rocky mountain became a national park
[{'answer': 'January 26 , 1915', 'provenance': [{'wikipedia_id': '285954', 'title': 'Rocky Mountain National Park', 'start_paragraph_id': 7, 'start_character': 220, 'end_paragraph_id': 7, 'end_character': 237, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '285954', 'title': 'Rocky Mountain National Park', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 548, 'bleu_score': 0.9248811440168371, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1235052745349451440}, 'section': 'Section::::Abstract.'}]}]