What was the first day cover cancellation for the University of Saskatchewan themed stamp?
CREATE TABLE "2007" (
  "date_of_issue" text,
  "theme" text,
  "denomination" text,
  "design" text,
  "illustration" text,
  "printing_process" text,
  "paper_type" text,
  "first_day_cover_cancellation" text
);
SELECT "first_day_cover_cancellation" FROM "2007" WHERE "theme"='University of Saskatchewan';