Who were the co-drivers for the Racing Organisation Course team in years before 2011, who had a position of DNF?
CREATE TABLE "24_hours_of_le_mans_results" (
  "year" real,
  "team" text,
  "co_drivers" text,
  "class" text,
  "laps" real,
  "pos" text,
  "class_pos" text
);
SELECT "co_drivers" FROM "24_hours_of_le_mans_results" WHERE "pos"='dnf' AND "year"<2011 AND "team"='racing organisation course';