Question: when was pot made illegal in the us
[{'answer': '1970', 'provenance': [{'wikipedia_id': '11164587', 'title': 'Legal history of cannabis in the United States', 'start_paragraph_id': 2, 'start_character': 123, 'end_paragraph_id': 2, 'end_character': 127, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '11164587', 'title': 'Legal history of cannabis in the United States', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 719, 'bleu_score': 0.982060959997838, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17230389300300548356}, 'section': 'Section::::Abstract.'}]}]