Question: when was the last time chelsea won the champions league
[{'answer': '2012', 'provenance': [{'wikipedia_id': '24118936', 'title': 'Chelsea F.C. in international football competitions', 'start_paragraph_id': 2, 'start_character': 200, 'end_paragraph_id': 2, 'end_character': 204, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]