Question: when was the first book of harry potter published
[{'answer': '1997', 'provenance': [{'wikipedia_id': '2387806', 'title': 'Harry Potter', 'start_paragraph_id': 2, 'start_character': 93, 'end_paragraph_id': 2, 'end_character': 97, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]