What is the most recent year of disaffiliation of a CHCH-TV station that affiliated after 2001?
CREATE TABLE "owned_and_operated" (
  "city_of_license_market" text,
  "station" text,
  "channel_tv_rf" text,
  "year_of_affiliation" real,
  "year_of_disaffiliation" real
);
SELECT MAX("year_of_disaffiliation") FROM "owned_and_operated" WHERE "station"='chch-tv' AND "year_of_affiliation">2001;