CREATE TABLE table_31391 ("Season" TEXT, "Season premiere" TEXT, "Season finale" TEXT, "TV season" TEXT, "Ranking" TEXT, "Viewers  ( in millions ) " TEXT)

What was the 2nd's season's ranking?
SELECT "Ranking" FROM table_31391 WHERE "Season" = '2nd'
SELECT "Ranking" FROM "table_31391" WHERE "Season" = '2nd'