How many times was the reader's vote na and the lifetime achievement na?
CREATE TABLE "previous_winners" (
  "year" real,
  "best_teenage_young_adult" text,
  "reader_s_vote" text,
  "best_non_fiction" text,
  "lifetime_achievement" text
);
SELECT COUNT("year") FROM "previous_winners" WHERE "reader_s_vote"='na' AND "lifetime_achievement"='na';