Question: what year did they stop making impala ss
[{'answer': '1969', 'provenance': [{'wikipedia_id': '284998', 'title': 'Chevrolet Impala', 'start_paragraph_id': 36, 'start_character': 464, 'end_paragraph_id': 36, 'end_character': 468, 'bleu_score': 1.0, 'section': 'Section::::Fourth generation (1965–1970).\n'}]}, {'provenance': [{'wikipedia_id': '284998', 'title': 'Chevrolet Impala', 'start_paragraph_id': 48, 'start_character': 0, 'end_paragraph_id': 48, 'end_character': 1064, 'bleu_score': 0.7891476117618751, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18333706352137076002}, 'section': 'Section::::Fourth generation (1965–1970).:Impala SS (1961–1969).\n'}]}]