Question: when was the last time oklahoma won the national championship
[{'answer': '2003', 'provenance': [{'wikipedia_id': '6321810', 'title': 'Oklahoma Sooners football', 'start_paragraph_id': 40, 'start_character': 2405, 'end_paragraph_id': 40, 'end_character': 2409, 'bleu_score': 1.0, 'section': 'Section::::History.:Bob Stoops era (1999–2016).:1999–2002: Return to glory.\n'}]}]