Question: when was the flow of the chicago river reversed
[{'answer': '1887', 'provenance': [{'wikipedia_id': '41962', 'title': 'Chicago River', 'start_paragraph_id': 2, 'start_character': 78, 'end_paragraph_id': 2, 'end_character': 82, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '1900', 'provenance': [{'wikipedia_id': '41962', 'title': 'Chicago River', 'start_paragraph_id': 2, 'start_character': 758, 'end_paragraph_id': 2, 'end_character': 762, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '41962', 'title': 'Chicago River', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1123, 'bleu_score': 0.718638081959843, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 897055836060338652}, 'section': 'Section::::Abstract.'}]}]