Question: when was neptune last visited by a spacecraft
[{'answer': '1989', 'provenance': [{'wikipedia_id': '12585410', 'title': 'Exploration of Neptune', 'start_paragraph_id': 1, 'start_character': 78, 'end_paragraph_id': 1, 'end_character': 82, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '12585410', 'title': 'Exploration of Neptune', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 353, 'bleu_score': 0.9645876452711911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4413610161542713693}, 'section': 'Section::::Abstract.'}]}]