What was the average mintage for that of artist Celia Godkin, before the year 2010?
CREATE TABLE "provincial_flowers" (
  "year" real,
  "artist" text,
  "composition" text,
  "mintage" real,
  "issue_price" text
);
SELECT AVG("mintage") FROM "provincial_flowers" WHERE "artist"='celia godkin' AND "year"<2010;