CREATE TABLE table_31324 ("Series #" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( million ) " TEXT)

How many millions of U.S viewers are there when the director is andy wolk?
SELECT "U.S. viewers (million)" FROM table_31324 WHERE "Directed by" = 'Andy Wolk'
SELECT "U.S. viewers (million)" FROM "table_31324" WHERE "Directed by" = 'Andy Wolk'