Question: when did purdue pharma begin manufacturing oxycontin in the united states
[{'answer': '1996', 'provenance': [{'wikipedia_id': '7484403', 'title': 'Purdue Pharma', 'start_paragraph_id': 17, 'start_character': 342, 'end_paragraph_id': 17, 'end_character': 346, 'bleu_score': 1.0, 'section': 'Section::::Controversy.\n'}]}, {'provenance': [{'wikipedia_id': '7484403', 'title': 'Purdue Pharma', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 416, 'bleu_score': 0.9679895851501501, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13070298905444542141}, 'section': 'Section::::Controversy.\n'}]}]