Question: when was the last perfect game thrown in baseball
[{'answer': 'August 15 , 2012', 'provenance': [{'wikipedia_id': '33940138', 'title': 'List of Major League Baseball perfect games', 'start_paragraph_id': 53, 'start_character': 3, 'end_paragraph_id': 53, 'end_character': 19, 'bleu_score': 1.0, 'section': 'Section::::Major League Baseball perfect games.:Modern era.:Félix Hernández.\n'}]}]