Question: when did o canada became the official national anthem
[{'answer': '1980', 'provenance': [{'wikipedia_id': '22504', 'title': 'O Canada', 'start_paragraph_id': 1, 'start_character': 862, 'end_paragraph_id': 1, 'end_character': 866, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '22504', 'title': 'O Canada', 'start_paragraph_id': 1, 'start_character': 3, 'end_paragraph_id': 1, 'end_character': 1028, 'bleu_score': 0.626096312564108, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5652786599866854865}, 'section': 'Section::::Abstract.'}]}]