CREATE TABLE table_2578 ("No. in series" TEXT, "No. in season" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

How many million U.s. Viewers watched episode 12 in the season?
SELECT "U.S. viewers (millions)" FROM table_2578 WHERE "No. in season" = '12'
SELECT "U.S. viewers (millions)" FROM "table_2578" WHERE "No. in season" = '12'