Tell me the date for rudolf caracciola for avusrennen
CREATE TABLE "non_championship_grands_prix" (
  "name" text,
  "circuit" text,
  "date" text,
  "winning_driver" text,
  "winning_constructor" text,
  "report" text
);
SELECT "date" FROM "non_championship_grands_prix" WHERE "winning_driver"='rudolf caracciola' AND "name"='avusrennen';