Question: how many costco's are there in the united states
[{'answer': '519'}, {'provenance': [{'wikipedia_id': '446056', 'title': 'Costco', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 480, 'bleu_score': 0.505480303391256, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5110183549639144721}, 'section': 'Section::::Abstract.'}]}]