Question: when was the east texas oil field discovered
[{'answer': '1930', 'provenance': [{'wikipedia_id': '4403401', 'title': 'East Texas Oil Field', 'start_paragraph_id': 1, 'start_character': 293, 'end_paragraph_id': 1, 'end_character': 297, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4403401', 'title': 'East Texas Oil Field', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 297, 'bleu_score': 0.52746415638626, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7741403460732223803}, 'section': 'Section::::Abstract.'}]}]