Question: when was the last time ku won the big 12 basketball tournament
[{'answer': '2018', 'provenance': [{'wikipedia_id': '9965271', 'title': "Big 12 Men's Basketball Tournament", 'start_paragraph_id': 5, 'start_character': 143, 'end_paragraph_id': 5, 'end_character': 147, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}]