What is the minimum MotoGP/500cc ranking?
CREATE TABLE "grand_prix_motorcycle_racing_world_champ" (
  "rank" real,
  "rider" text,
  "country" text,
  "winning_span" text,
  "moto_gp_500cc" real,
  "350cc" real,
  "moto2_250cc" real,
  "moto3_125cc" real,
  "80cc_50cc" real,
  "total" real
);
SELECT MIN("moto_gp_500cc") FROM "grand_prix_motorcycle_racing_world_champ";