What is the average year having a rank among provinces over 5 and ten-year percentage change of 67.3?
CREATE TABLE "demography" (
  "year" real,
  "population" real,
  "five_year_pct_change" text,
  "ten_year_pct_change" text,
  "rank_among_provinces" real
);
SELECT AVG("year") FROM "demography" WHERE "ten_year_pct_change"='67.3' AND "rank_among_provinces">5;