What was the average year that the Nashville Metros did not qualify for the Playoffs, did not qualify for the Open Cup, and had the Regular Season 7th, Southeast?
CREATE TABLE "year_by_year" (
  "year" real,
  "division" text,
  "league" text,
  "regular_season" text,
  "playoffs" text,
  "open_cup" text
);
SELECT AVG("year") FROM "year_by_year" WHERE "playoffs"='did not qualify' AND "open_cup"='did not qualify' AND "regular_season"='7th, southeast';