Question: what nba team has the highest winning percentage
[{'answer': 'San Antonio Spurs', 'provenance': [{'wikipedia_id': '46523941', 'title': 'List of all-time NBA win-loss records', 'start_paragraph_id': 2, 'start_character': 4, 'end_paragraph_id': 2, 'end_character': 21, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]