In what Year of Census or Estimate is the Toronto Population larger than 1,556,396?
CREATE TABLE "most_populous_cities" (
  "rank" real,
  "city" text,
  "population" real,
  "year_of_census_or_estimate" real,
  "country" text
);
SELECT SUM("year_of_census_or_estimate") FROM "most_populous_cities" WHERE "population">'1,556,396' AND "city"='toronto';