Question: when did great britain join the european union
[{'answer': '1 January 1973', 'provenance': [{'wikipedia_id': '54490420', 'title': 'History of European Union–United Kingdom relations', 'start_paragraph_id': 5, 'start_character': 347, 'end_paragraph_id': 5, 'end_character': 361, 'bleu_score': 1.0, 'section': 'Section::::EU roots and British accession (1957–1973).\n'}]}, {'provenance': [{'wikipedia_id': '54490420', 'title': 'History of European Union–United Kingdom relations', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 361, 'bleu_score': 0.9679895851501501, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7800987182556791987}, 'section': 'Section::::EU roots and British accession (1957–1973).\n'}]}]