CREATE TABLE "24_hours_of_le_mans_results" (
  "year" real,
  "team" text,
  "co_drivers" text,
  "class" text,
  "laps" real,
  "pos" text,
  "class_pos" text
);

Question: What year has WSC class?
SQL: SELECT "year" FROM "24_hours_of_le_mans_results" WHERE "class"='wsc';