How many years of introduction does the Neal Submachine Gun have?
CREATE TABLE "table1_29474407_11" (
  "name_designation" text,
  "year_of_intro" real,
  "country_of_origin" text,
  "primary_cartridge" text,
  "major_users" text
);
SELECT COUNT("year_of_intro") FROM "table1_29474407_11" WHERE "name_designation"='Neal submachine gun';