Question: when was the last nuclear plant built in the us
[{'answer': 'September 2017'}, {'provenance': [{'wikipedia_id': '4131402', 'title': 'Nuclear power in the United States', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 284, 'bleu_score': 0.8834365670857711, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6731918476748238945}, 'section': 'Section::::Abstract.'}]}]