Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_31 (rank INTEGER, headquarters VARCHAR, market_value__billion_$_ VARCHAR)
### Question:
What is the average rank for USA when the market value is 407.2 billion?
### Answer:
SELECT AVG(rank) FROM table_name_31 WHERE headquarters = "usa" AND market_value__billion_$_ > 407.2