On what day was the score of 1–6 6–1 3–6 achieved?
CREATE TABLE "singles_6_6" (
  "outcome" text,
  "date" text,
  "tournament" text,
  "surface" text,
  "opponent" text,
  "score" text
);
SELECT "date" FROM "singles_6_6" WHERE "score"='1–6 6–1 3–6';