Question: when was the john hancock building in chicago built
[{'answer': '1969', 'provenance': [{'wikipedia_id': '40420', 'title': 'John Hancock Center', 'start_paragraph_id': 6, 'start_character': 165, 'end_paragraph_id': 6, 'end_character': 169, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}]