Question: when did oregon ban self service gas stations
[{'answer': '1951', 'provenance': [{'wikipedia_id': '22320226', 'title': 'Filling station attendant', 'start_paragraph_id': 12, 'start_character': 43, 'end_paragraph_id': 12, 'end_character': 47, 'bleu_score': 1.0, 'section': 'Section::::History.:Current status.:United States.\n'}]}]