Question: when did the nba institute the shot clock
[{'answer': '1954 -- 55'}, {'provenance': [{'wikipedia_id': '1002256', 'title': 'Shot clock', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 489, 'bleu_score': 0.8334803611033941, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6582593260358316980}, 'section': 'Section::::History.:Use and reaction.\n'}]}]