Question: when did barcelona last win the champions league
[{'answer': '2015', 'provenance': [{'wikipedia_id': '21227395', 'title': 'FC Barcelona in international football competitions', 'start_paragraph_id': 3, 'start_character': 177, 'end_paragraph_id': 3, 'end_character': 181, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21227395', 'title': 'FC Barcelona in international football competitions', 'start_paragraph_id': 13, 'start_character': 0, 'end_paragraph_id': 13, 'end_character': 642, 'bleu_score': 0.916577979929009, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2912605861497623572}, 'section': 'Section::::European Cup / UEFA Champions League.\n'}]}]