What series had Joan Tena in sixth place?
CREATE TABLE "series_summary" (
  "series" real,
  "year" text,
  "winner" text,
  "runner_up" text,
  "third_place" text,
  "fourth_place" text,
  "fifth_place" text,
  "sixth_place" text,
  "host" text
);
SELECT SUM("series") FROM "series_summary" WHERE "sixth_place"='joan tena';