CREATE TABLE table_3573 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT, "U.S. viewers  ( millions ) " TEXT)

How many production codes had a US viewership of 4.43 million?
SELECT COUNT("Production code") FROM table_3573 WHERE "U.S. viewers (millions)" = '4.43'
SELECT COUNT("Production code") FROM "table_3573" WHERE "U.S. viewers (millions)" = '4.43'