Question: when was the stop and frisk policy started
[{'answer': '1968', 'provenance': [{'wikipedia_id': '35257558', 'title': 'Stop-and-frisk in New York City', 'start_paragraph_id': 4, 'start_character': 93, 'end_paragraph_id': 4, 'end_character': 97, 'bleu_score': 1.0, 'section': 'Section::::Legal background of stop-and-frisk.\n'}]}, {'provenance': [{'wikipedia_id': '35257558', 'title': 'Stop-and-frisk in New York City', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 713, 'bleu_score': 0.984062469849008, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5027852041453560523}, 'section': 'Section::::Legal background of stop-and-frisk.\n'}]}]