What is the 2006 that has a 2r in 2004, and a 2r in 2005?
CREATE TABLE "doubles_performance_timeline" (
  "tournament" text,
  "2004" text,
  "2005" text,
  "2006" text,
  "2007" text
);
SELECT "2006" FROM "doubles_performance_timeline" WHERE "2004"='2r' AND "2005"='2r';