CREATE TABLE table_204_996 (id DECIMAL, "no." TEXT, "air date" TEXT, "network" TEXT, "household\ rating" DECIMAL, "viewers\ ( millions ) " TEXT)

which network had the all time top number of viewers ?
SELECT "network" FROM table_204_996 ORDER BY "viewers\n(millions)" DESC LIMIT 1
SELECT "network" FROM "table_204_996" ORDER BY "viewers\n(millions)" DESC NULLS LAST LIMIT 1