Question: when did dean martin sing let it snow
[{'answer': '1959', 'provenance': [{'wikipedia_id': '38549132', 'title': 'The Dean Martin Christmas Album', 'start_paragraph_id': 2, 'start_character': 153, 'end_paragraph_id': 2, 'end_character': 157, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '38549132', 'title': 'The Dean Martin Christmas Album', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 258, 'bleu_score': 0.9560167778278961, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13720949622193793399}, 'section': 'Section::::Abstract.'}]}]