CREATE TABLE table_31178 ("Athlete" TEXT, "Event" TEXT, "Elimination Poule" TEXT, "Round of 16" TEXT, "Quarterfinals" TEXT, "Semifinals" TEXT, "Final" TEXT)

How many athletes were named federico muller?
SELECT COUNT("Quarterfinals") FROM table_31178 WHERE "Athlete" = 'Federico Muller'
SELECT COUNT("Quarterfinals") FROM "table_31178" WHERE "Athlete" = 'Federico Muller'