What is the total count of net gross in 1957?
CREATE TABLE "list_of_highest_grossing_bollywood_films" (
  "year" real,
  "movie" text,
  "record_held" text,
  "studio_s" text,
  "nett_gross" real
);
SELECT COUNT("nett_gross") FROM "list_of_highest_grossing_bollywood_films" WHERE "year"=1957;