Question: when did puerto rico became a us commonwealth
[{'answer': '1952', 'provenance': [{'wikipedia_id': '23041', 'title': 'Puerto Rico', 'start_paragraph_id': 4, 'start_character': 788, 'end_paragraph_id': 4, 'end_character': 792, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '23041', 'title': 'Puerto Rico', 'start_paragraph_id': 65, 'start_character': 0, 'end_paragraph_id': 65, 'end_character': 428, 'bleu_score': 0.968982777549629, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12022768352982168641}, 'section': 'Section::::History.:American colony (1898–present).:"Estado Libre Asociado".\n'}]}]