Question: when did they start working on mount rushmore
[{'answer': '1927', 'provenance': [{'wikipedia_id': '17583989', 'title': 'Construction of Mount Rushmore', 'start_paragraph_id': 1, 'start_character': 73, 'end_paragraph_id': 1, 'end_character': 77, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '17583989', 'title': 'Construction of Mount Rushmore', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 85, 'bleu_score': 0.861173529963367, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1841175821114843484}, 'section': 'Section::::Abstract.'}]}]