What is the total number of years that Scuderia Guastalla was an entrant?
CREATE TABLE "complete_formula_one_world_championship_" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" text
);
SELECT COUNT("year") FROM "complete_formula_one_world_championship_" WHERE "entrant"='scuderia guastalla';