Question: since when is puerto rico part of the us
[{'answer': 'April 11 , 1899', 'provenance': [{'wikipedia_id': '23041', 'title': 'Puerto Rico', 'start_paragraph_id': 43, 'start_character': 292, 'end_paragraph_id': 43, 'end_character': 307, 'bleu_score': 1.0, 'section': 'Section::::History.:American colony (1898–present).\n'}]}, {'provenance': [{'wikipedia_id': '23041', 'title': 'Puerto Rico', 'start_paragraph_id': 43, 'start_character': 0, 'end_paragraph_id': 43, 'end_character': 379, 'bleu_score': 0.970795021215021, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3112122962827601137}, 'section': 'Section::::History.:American colony (1898–present).\n'}]}]