What is the 2010 of the Grand Slam Tournaments in 2011?
CREATE TABLE "singles_performance_timeline" (
  "tournament" text,
  "2007" text,
  "2008" text,
  "2009" text,
  "2010" text,
  "2011" text,
  "2012" text
);
SELECT "2010" FROM "singles_performance_timeline" WHERE "2011"='grand slam tournaments';