Question: when did new york islanders join the nhl
[{'answer': '1972', 'provenance': [{'wikipedia_id': '66880', 'title': 'New York Islanders', 'start_paragraph_id': 2, 'start_character': 24, 'end_paragraph_id': 2, 'end_character': 28, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '66880', 'title': 'New York Islanders', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 666, 'bleu_score': 0.981898582188057, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13420445728536325787}, 'section': 'Section::::Abstract.'}]}]