What is 2011, when Tournament is "Year-End Ranking"?
CREATE TABLE "singles_performance_timeline" (
  "tournament" text,
  "2008" text,
  "2009" text,
  "2010" text,
  "2011" text,
  "2012" text
);
SELECT "2011" FROM "singles_performance_timeline" WHERE "tournament"='year-end ranking';