What's the lowest number of total passengers (millions) for an annual entry/exit of 36.609?
CREATE TABLE "references" (
  "rank" real,
  "railway_station" text,
  "annual_entry_exit_millions_2011_12" real,
  "annual_interchanges_millions_2011_12" real,
  "total_passengers_millions_2011_12" real,
  "location" text,
  "number_of_platforms" real
);
SELECT MIN("total_passengers_millions_2011_12") FROM "references" WHERE "annual_entry_exit_millions_2011_12"=36.609;