CREATE TABLE table_203_160 (id DECIMAL, "rank" DECIMAL, "heat" DECIMAL, "nation" TEXT, "competitors" TEXT, "time" TEXT, "notes" TEXT)

which country took the least amount of time ?
SELECT "nation" FROM table_203_160 ORDER BY "time" LIMIT 1
SELECT "nation" FROM "table_203_160" ORDER BY "time" NULLS FIRST LIMIT 1