Question: how many cities does the us have with a population of over 1 million
[{'answer': '10', 'provenance': [{'wikipedia_id': '1649321', 'title': 'List of United States cities by population', 'start_paragraph_id': 4, 'start_character': 105, 'end_paragraph_id': 4, 'end_character': 107, 'bleu_score': 1.0, 'section': 'Section::::United States.\n'}]}]