Question: when did the bears start playing at soldier field
[{'answer': '1971', 'provenance': [{'wikipedia_id': '509225', 'title': 'Soldier Field', 'start_paragraph_id': 1, 'start_character': 218, 'end_paragraph_id': 1, 'end_character': 222, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '509225', 'title': 'Soldier Field', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 826, 'bleu_score': 0.925284102042305, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2165739346579718458}, 'section': 'Section::::History.:Chicago Bears move in.\n'}]}]