CREATE TABLE table_9481 ("Place" TEXT, "Player" TEXT, "Country" TEXT, "Score" FLOAT, "To par" TEXT)

When Tom Purtzer of the United States played what is the maximum score?
SELECT MAX("Score") FROM table_9481 WHERE "Country" = 'united states' AND "Player" = 'tom purtzer'
SELECT MAX("Score") FROM "table_9481" WHERE "Country" = 'united states' AND "Player" = 'tom purtzer'