Which PD per game has a Rank smaller than 4, a Winning % of 78.6%, a Streak of w1, and a PA per game smaller than 81.5?
CREATE TABLE "2009_nbl_ladder_championship_round" (
  "rank" real,
  "team" text,
  "played" real,
  "loss" real,
  "last_5" text,
  "streak" text,
  "pf_per_game" real,
  "pa_per_game" real,
  "pd_per_game" real,
  "winning_pct" text
);
SELECT MIN("pd_per_game") FROM "2009_nbl_ladder_championship_round" WHERE "rank"<4 AND "winning_pct"='78.6%' AND "streak"='w1' AND "pa_per_game"<81.5;