What is the average number of years associated with 51 games tied and over 1184 total games?
CREATE TABLE "ncaa_division_i_fbs_football_win_loss_re" (
  "pac_12" text,
  "lost" real,
  "tied" real,
  "pct" real,
  "years" real,
  "total_games" real
);
SELECT AVG("years") FROM "ncaa_division_i_fbs_football_win_loss_re" WHERE "tied"=51 AND "total_games">1184;