How many 2nd legs had an aggregate of 2-4?
CREATE TABLE "winners_knockout" (
  "home_1st_leg" text,
  "home_2nd_leg" text,
  "1st_leg" text,
  "2nd_leg" text,
  "aggregate" text
);
SELECT COUNT("2nd_leg") FROM "winners_knockout" WHERE "aggregate"='2-4';