What is the average number of ties for years with more than 19 wins?
CREATE TABLE "performance_summary_in_indian_premier_le" (
  "year" text,
  "matches" real,
  "wins" real,
  "losses" real,
  "no_result" real,
  "tied" real,
  "success_rate" text
);
SELECT AVG("tied") FROM "performance_summary_in_indian_premier_le" WHERE "wins">19;