Question: when did the pittsburgh penguins win their first stanley cup
[{'answer': '1991', 'provenance': [{'wikipedia_id': '66964', 'title': 'Pittsburgh Penguins', 'start_paragraph_id': 2, 'start_character': 636, 'end_paragraph_id': 2, 'end_character': 640, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '66964', 'title': 'Pittsburgh Penguins', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1021, 'bleu_score': 0.6590029879143781, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13922971270455788035}, 'section': 'Section::::Abstract.'}]}]