Question: when did the canadian flag change to the maple leaf
[{'answer': 'February 15 , 1965', 'provenance': [{'wikipedia_id': '97066', 'title': 'Flag of Canada', 'start_paragraph_id': 2, 'start_character': 388, 'end_paragraph_id': 2, 'end_character': 406, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '97066', 'title': 'Flag of Canada', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 473, 'bleu_score': 0.976043556018343, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4497488040241062687}, 'section': 'Section::::Abstract.'}]}]