In what year was the venue Gold Coast and the Men's 35s NSW?
CREATE TABLE "results_of_the_national_championships_19" (
  "year" real,
  "venue" text,
  "men_s_open" text,
  "women_s_open" text,
  "men_s_35s" text
);
SELECT SUM("year") FROM "results_of_the_national_championships_19" WHERE "venue"='gold coast' AND "men_s_35s"='nsw';