Question: when was the last time north korea participated in the winter olympics
[{'answer': '2018', 'provenance': [{'wikipedia_id': '34069', 'title': 'Winter Olympic Games', 'start_paragraph_id': 4, 'start_character': 517, 'end_paragraph_id': 4, 'end_character': 521, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '34069', 'title': 'Winter Olympic Games', 'start_paragraph_id': 48, 'start_character': 0, 'end_paragraph_id': 48, 'end_character': 606, 'bleu_score': 0.980097014099621, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8965410573081466837}, 'section': 'Section::::History.:21st century.:2014 to 2018.\n'}]}]