what year did north carolina institution join the acc?
CREATE TABLE "member_schools" (
  "institution" text,
  "nickname" text,
  "location" text,
  "founded" real,
  "joined_acc" real,
  "school_type" text,
  "acc_football_titles" real
);
SELECT MAX("joined_acc") FROM "member_schools" WHERE "institution"='North Carolina';