CREATE TABLE table_name_90 (total INTEGER, year_of_census VARCHAR(255), serbs VARCHAR(255))
What is the average total of the census after 1971 with 10,412 (32.88%) Serbs?
    
SQL: SELECT AVG(total) FROM table_name_90 WHERE year_of_census > 1971 AND serbs = "10,412 (32.88%)"