Question: when was the last time the bombers won a grey cup
[{'answer': '1990', 'provenance': [{'wikipedia_id': '254173', 'title': 'Winnipeg Blue Bombers', 'start_paragraph_id': 3, 'start_character': 115, 'end_paragraph_id': 3, 'end_character': 119, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]