Question: when did the deepwater horizon oil spill end
[{'answer': 'September 19 , 2010', 'provenance': [{'wikipedia_id': '27046954', 'title': 'Deepwater Horizon oil spill', 'start_paragraph_id': 25, 'start_character': 248, 'end_paragraph_id': 25, 'end_character': 267, 'bleu_score': 1.0, 'section': 'Section::::Efforts to stem the flow of oil.:Well declared "effectively dead".\n'}]}, {'provenance': [{'wikipedia_id': '27046954', 'title': 'Deepwater Horizon oil spill', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 750, 'bleu_score': 0.817665646349356, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4741790509556990341}, 'section': 'Section::::Abstract.'}]}]