Question: when was the white cliffs of dover written
[{'answer': '1941', 'provenance': [{'wikipedia_id': '11565332', 'title': "(There'll Be Bluebirds Over) The White Cliffs of Dover", 'start_paragraph_id': 1, 'start_character': 100, 'end_paragraph_id': 1, 'end_character': 104, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '11565332', 'title': "(There'll Be Bluebirds Over) The White Cliffs of Dover", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 274, 'bleu_score': 0.9632870032952191, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5536595717013154186}, 'section': 'Section::::Abstract.'}]}]