CREATE TABLE table_204_521 (id DECIMAL, "rank" DECIMAL, "name" TEXT, "nationality" TEXT, "time  ( hand ) " TEXT, "notes" TEXT)

how many times did the united states rank ?
SELECT COUNT(*) FROM table_204_521 WHERE "nationality" = 'united states' AND NOT "rank" IS NULL
SELECT COUNT(*) FROM "table_204_521" WHERE "nationality" = 'united states' AND NOT "rank" IS NULL