What is the population on average with a per capita of 1,158, and a 2011 GDP less than 6,199?
CREATE TABLE "economic_data" (
  "country" text,
  "population" real,
  "gdp_2011_in_millions_usd" real,
  "gdp_2012_in_millions_usd" real,
  "per_capita" real
);
SELECT AVG("population") FROM "economic_data" WHERE "per_capita"='1,158' AND "gdp_2011_in_millions_usd"<'6,199';