What is the total time in office of the prime minister from the liberal party and left office in 19 December 1967?
CREATE TABLE "rank_by_time_in_office" (
  "rank" real,
  "prime_minister" text,
  "party" text,
  "assumed_office" text,
  "left_office" text,
  "total_time_in_office" text
);
SELECT "total_time_in_office" FROM "rank_by_time_in_office" WHERE "party"='liberal' AND "left_office"='19 december 1967';