Question: when did the cowboys become america's team
[{'answer': '1978', 'provenance': [{'wikipedia_id': '1817340', 'title': "America's Team", 'start_paragraph_id': 2, 'start_character': 40, 'end_paragraph_id': 2, 'end_character': 44, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]