Question: when did the bill cosby show first air
[{'answer': 'September 20 , 1984', 'provenance': [{'wikipedia_id': '170325', 'title': 'The Cosby Show', 'start_paragraph_id': 1, 'start_character': 126, 'end_paragraph_id': 1, 'end_character': 145, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '170325', 'title': 'The Cosby Show', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 251, 'bleu_score': 0.740947446142591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5699304661246457318}, 'section': 'Section::::Abstract.'}]}]