Question: when was the elevated train in chicago built
[{'answer': '1892', 'provenance': [{'wikipedia_id': '412649', 'title': 'Chicago "L"', 'start_paragraph_id': 2, 'start_character': 203, 'end_paragraph_id': 2, 'end_character': 207, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '412649', 'title': 'Chicago "L"', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 311, 'bleu_score': 0.8289279069665341, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1902485946140264044}, 'section': 'Section::::Abstract.'}]}]