Question: when were chelsea promoted to the premier league
[{'answer': '1991 -- 92'}, {'provenance': [{'wikipedia_id': '4686545', 'title': 'History of Chelsea F.C.', 'start_paragraph_id': 78, 'start_character': 322, 'end_paragraph_id': 78, 'end_character': 995, 'bleu_score': 0.576502126972635, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10740422123957104942}, 'section': 'Section::::The 1990s: Back on track.\n'}]}]