what is the average total when bronze is more than 0, gold is 0, the nation is united states (usa) and silver is 0?
CREATE TABLE "medal_count_by_country" (
  "rank" real,
  "nation" text,
  "gold" real,
  "silver" real,
  "bronze" real,
  "total" real
);
SELECT AVG("total") FROM "medal_count_by_country" WHERE "bronze">0 AND "gold"=0 AND "nation"='united states (usa)' AND "silver"<0;