Question: when did they start spraying agent orange in vietnam
[{'answer': '1961', 'provenance': [{'wikipedia_id': '2547', 'title': 'Agent Orange', 'start_paragraph_id': 1, 'start_character': 243, 'end_paragraph_id': 1, 'end_character': 247, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2547', 'title': 'Agent Orange', 'start_paragraph_id': 1, 'start_character': 6, 'end_paragraph_id': 1, 'end_character': 528, 'bleu_score': 0.815605276229417, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13075321123483833806}, 'section': 'Section::::Abstract.'}]}]