Question: when did the last transformers movie come out
[{'answer': 'June 21 , 2017', 'provenance': [{'wikipedia_id': '22783445', 'title': 'Transformers (film series)', 'start_paragraph_id': 33, 'start_character': 3, 'end_paragraph_id': 33, 'end_character': 17, 'bleu_score': 1.0, 'section': 'Section::::Films.:Future.\n'}]}]