What is the largest year with an Entrant of ron harris / team lotus?
CREATE TABLE "formula_one_world_championship_results" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT MAX("year") FROM "formula_one_world_championship_results" WHERE "entrant"='ron harris / team lotus';