What year was the name mount roskill grammar school?
CREATE TABLE "secondary_schools" (
  "name" text,
  "years" text,
  "gender" text,
  "local_board" text,
  "suburb" text,
  "authority" text,
  "decile" text,
  "roll" real
);
SELECT "years" FROM "secondary_schools" WHERE "name"='mount roskill grammar school';