Question: when did kiev become the capital of ukraine
[{'answer': '1991', 'provenance': [{'wikipedia_id': '2449699', 'title': 'History of Kiev', 'start_paragraph_id': 3, 'start_character': 657, 'end_paragraph_id': 3, 'end_character': 661, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2449699', 'title': 'History of Kiev', 'start_paragraph_id': 69, 'start_character': 0, 'end_paragraph_id': 69, 'end_character': 148, 'bleu_score': 0.9214109120166031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2438128846483677726}, 'section': 'Section::::Independent Ukraine.\n'}]}]