Which 2006 tournament had a 4R performance in 2001?
CREATE TABLE "major_tournament_singles_performance_tim" (
  "tournament" text,
  "1998" text,
  "1999" text,
  "2000" text,
  "2001" text,
  "2002" text,
  "2003" text,
  "2004" text,
  "2005" text,
  "2006" text,
  "2007" text,
  "career_sr" text
);
SELECT "2006" FROM "major_tournament_singles_performance_tim" WHERE "2001"='4r';