Table schema:
CREATE TABLE table_name_99 (total INTEGER, silver VARCHAR, nation VARCHAR, bronze VARCHAR, gold VARCHAR)

Question: what is the average total when bronze is more than 0, gold is 0, the nation is united states (usa) and silver is 0?
SQL: SELECT AVG(total) FROM table_name_99 WHERE bronze > 0 AND gold = 0 AND nation = "united states (usa)" AND silver < 0