CREATE TABLE table_name_91 (income_inequality_1994_2011__latest_available_ VARCHAR2, population_2011 VARCHAR2)

What is the latest available income inequality for the country with a population of 21,315,135?
SELECT income_inequality_1994_2011__latest_available_ FROM table_name_91 WHERE population_2011 = "21,315,135"
SELECT "income_inequality_1994_2011__latest_available_" FROM "table_name_91" WHERE "21,315,135" = "population_2011"