Question: when was the last time alabama won a national championship
[{'answer': '2012', 'provenance': [{'wikipedia_id': '7751357', 'title': 'Alabama Crimson Tide football', 'start_paragraph_id': 12, 'start_character': 185, 'end_paragraph_id': 12, 'end_character': 189, 'bleu_score': 1.0, 'section': 'Section::::History.:National championships.\n'}]}]