Question: when was the first 50 cent piece made
[{'answer': '1964', 'provenance': [{'wikipedia_id': '374699', 'title': 'Half dollar (United States coin)', 'start_paragraph_id': 1, 'start_character': 441, 'end_paragraph_id': 1, 'end_character': 445, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]