2013 of 4–4 is involved in what 2006?
CREATE TABLE "grand_slam_tournaments" (
  "tournament" text,
  "1998" text,
  "2000" text,
  "2001" text,
  "2002" text,
  "2003" text,
  "2004" text,
  "2005" text,
  "2006" text,
  "2007" text,
  "2008" text,
  "2009" text,
  "2010" text,
  "2011" text,
  "2012" text,
  "2013" text
);
SELECT "2006" FROM "grand_slam_tournaments" WHERE "2013"='4–4';