CREATE TABLE table_203_653 (id DECIMAL, "rank" DECIMAL, "nation" TEXT, "gold" DECIMAL, "silver" DECIMAL, "bronze" DECIMAL, "total" DECIMAL)

what country with more than 20 total medals has the least amount of silver medals ?
SELECT "nation" FROM table_203_653 WHERE "total" > 20 ORDER BY "silver" LIMIT 1
SELECT "nation" FROM "table_203_653" WHERE "total" > 20 ORDER BY "silver" NULLS FIRST LIMIT 1