What is the average total of the census after 1971 with 10,412 (32.88%) Serbs?
CREATE TABLE "national_structure_of_the_population_in_" (
  "year_of_census" real,
  "total" real,
  "croats" text,
  "serbs" text,
  "others" text
);
SELECT AVG("total") FROM "national_structure_of_the_population_in_" WHERE "year_of_census">1971 AND "serbs"='10,412 (32.88%)';