What is the 1976 value of the Australian Open?
CREATE TABLE "singles_performance_timeline" (
  "tournament" text,
  "1972" text,
  "1973" text,
  "1974" text,
  "1975" text,
  "1976" text,
  "1977" text,
  "1978" text
);
SELECT "1976" FROM "singles_performance_timeline" WHERE "tournament"='australian open';