CREATE TABLE table_204_849 (id DECIMAL, "rank" DECIMAL, "name" TEXT, "nationality" TEXT, "time" TEXT)

what counties had the least participants for the race ?
SELECT "nationality" FROM table_204_849 GROUP BY "nationality" HAVING COUNT("name") = (SELECT COUNT("name") FROM table_204_849 GROUP BY "nationality" ORDER BY COUNT("name") LIMIT 1)
SELECT "nationality" FROM "table_204_849" GROUP BY "nationality" HAVING COUNT("name") = (SELECT COUNT("name") FROM "table_204_849" GROUP BY "nationality" ORDER BY COUNT("name") NULLS FIRST LIMIT 1)