In how many different years was the team nicknamed Comets founded?
CREATE TABLE "division_ii" (
  "institution" text,
  "location" text,
  "founded" real,
  "affiliation" text,
  "enrollment" real,
  "team_nickname" text,
  "primary_conference" text
);
SELECT COUNT("founded") FROM "division_ii" WHERE "team_nickname"='Comets';