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

which network has the most airings ?
SELECT "network" FROM table_204_996 GROUP BY "network" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "network" FROM "table_204_996" GROUP BY "network" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1