What is the surface for the year 2001?
CREATE TABLE "singles_6_2_titles_4_runner_ups" (
  "outcome" text,
  "year" real,
  "championship" text,
  "surface" text,
  "opponent_in_the_final" text,
  "score_in_the_final" text
);
SELECT "surface" FROM "singles_6_2_titles_4_runner_ups" WHERE "year"=2001;