What is the average year with an average start smaller than 6.3 and fewer than 0 wins?
CREATE TABLE "nascar_nationwide_series" (
  "year" real,
  "starts" real,
  "wins" real,
  "top_5" real,
  "top_10" real,
  "poles" real,
  "avg_start" real,
  "avg_finish" real,
  "winnings" text,
  "position" text
);
SELECT AVG("year") FROM "nascar_nationwide_series" WHERE "avg_start"<6.3 AND "wins"<0;