What's the smallest number of bronze medals that any one if the ensembles has? 
{'header': ['Ensemble', 'Gold Medals', 'Silver Medals', 'Bronze Medals', 'Total Medals'], 'page_title': 'Winter Guard International', 'page_id': '', 'types': ['text', 'real', 'real', 'real', 'real'], 'id': '1-1305623-6', 'section_title': 'Percussion Independent World Class', 'caption': 'Percussion Independent World Class', 'rows': [['Aimachi', '0', '0', '3', '3'], ['Atlanta Rhythm', '1', '0', '0', '1'], ['Black Knights', '0', '1', '0', '1'], ['Blue Knights World', '4', '5', '2', '11'], ['Capital Regiment', '0', '0', '1', '1'], ['Sacramento Freelancers', '0', '1', '2', '3'], ['Mandarins', '0', '0', '1', '1'], ['Music City Mystique', '7', '3', '5', '15'], ['Pulse Percussion', '1', '0', '2', '3'], ['Rhythm X', '3', '3', '1', '7'], ['Riverside Community College', '4', '5', '0', '9'], ['Spirit', '0', '0', '1', '1']], 'name': 'table_1305623_6'}