What year is associated with a drama desk award ceremony and a Category of outstanding featured actress in a musical?
CREATE TABLE "awards_and_nominations" (
  "year" real,
  "award_ceremony" text,
  "category" text,
  "nominee" text,
  "result" text
);
SELECT AVG("year") FROM "awards_and_nominations" WHERE "award_ceremony"='drama desk award' AND "category"='outstanding featured actress in a musical';