Question: when did the panama canal start being built
[{'answer': '1881', 'provenance': [{'wikipedia_id': '24849', 'title': 'Panama Canal', 'start_paragraph_id': 2, 'start_character': 34, 'end_paragraph_id': 2, 'end_character': 38, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '24849', 'title': 'Panama Canal', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 541, 'bleu_score': 0.978138775770484, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12131746617521914074}, 'section': 'Section::::Abstract.'}]}]