When the Year is over 2008, what is the highest Mintage for the Royal Canadian Mint Engravers Artist?
CREATE TABLE "500_dollars" (
  "year" real,
  "artist" text,
  "composition" text,
  "mintage" real,
  "issue_price" text
);
SELECT MAX("mintage") FROM "500_dollars" WHERE "artist"='royal canadian mint engravers' AND "year">2008;