What is the 2006 sum with a rank 1 and more than 6758845 in 1996?
CREATE TABLE "cities_over_1_000_000_population" (
  "rank" real,
  "city" text,
  "province" text,
  "date_of_official_foundation_of_municipality" real,
  "2006" real,
  "1996" real,
  "1986" real,
  "1976" real,
  "1966" real,
  "1956" real
);
SELECT SUM("2006") FROM "cities_over_1_000_000_population" WHERE "rank"=1 AND "1996">6758845;