what is 1955 when 1961 is n/a?
CREATE TABLE "grand_tour_results_timeline" (
  "1953" text,
  "1954" text,
  "1955" text,
  "1956" text,
  "1957" text,
  "1958" text,
  "1959" text,
  "1960" text,
  "1961" text,
  "1962" text,
  "1963" text
);
SELECT "1955" FROM "grand_tour_results_timeline" WHERE "1961"='n/a';