Question: when was the last time the sixers won a championship
[{'answer': '1983', 'provenance': [{'wikipedia_id': '72857', 'title': 'Philadelphia 76ers', 'start_paragraph_id': 2, 'start_character': 451, 'end_paragraph_id': 2, 'end_character': 455, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]