Question: what percentage is the black population in the united states
[{'answer': '12.7 %', 'provenance': [{'wikipedia_id': '3058522', 'title': 'Race and ethnicity in the United States', 'start_paragraph_id': 3, 'start_character': 118, 'end_paragraph_id': 3, 'end_character': 126, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '3058522', 'title': 'Race and ethnicity in the United States', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 418, 'bleu_score': 0.671915612470616, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13838670809354133174}, 'section': 'Section::::Abstract.'}]}]