What is thea year the road closed April 13?
CREATE TABLE "statistics" (
  "year" real,
  "road_opened" text,
  "road_closed" text,
  "freight_carried_s_tonne" real,
  "super_b_capacity_reached_citation_needed" text,
  "number_of_truck_loads_north" real
);
SELECT MAX("year") FROM "statistics" WHERE "road_closed"='April 13';