what is the highest year that the U.S. captain is ken venturi?
CREATE TABLE "results" (
  "year" real,
  "venue" text,
  "location" text,
  "winning_team" text,
  "score" text,
  "u_s_captain" text,
  "international_captain" text
);
SELECT MAX("year") FROM "results" WHERE "u_s_captain"='ken venturi';