Question: when did the ar-15 first go on sale
[{'answer': '1959', 'provenance': [{'wikipedia_id': '904916', 'title': 'ArmaLite AR-15', 'start_paragraph_id': 1, 'start_character': 132, 'end_paragraph_id': 1, 'end_character': 136, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]