What is the latest year of a gratitude type mission with 99 in the entourage?
CREATE TABLE "ry_ky_an_missions_to_edo" (
  "year" real,
  "mission_type" text,
  "shogun" text,
  "ry_ky_an_king" text,
  "lead_envoy" text,
  "number_in_entourage" text
);
SELECT MAX("year") FROM "ry_ky_an_missions_to_edo" WHERE "number_in_entourage"='99' AND "mission_type"='gratitude';