How many million viewers watched the season finale on March 12, 1979?
CREATE TABLE "season_ratings" (
  "season" text,
  "ep_num" real,
  "season_premiere" text,
  "season_finale" text,
  "ranking" text,
  "viewers_households_in_millions" text,
  "rating" text
);
SELECT "viewers_households_in_millions" FROM "season_ratings" WHERE "season_finale"='march 12, 1979';