CREATE TABLE table_204_678 (id DECIMAL, "record" TEXT, "athlete" TEXT, "nation" TEXT, "venue" TEXT, "date" TEXT, "#" DECIMAL)

which nation has set the record the most times ?
SELECT "nation" FROM table_204_678 GROUP BY "nation" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "nation" FROM "table_204_678" GROUP BY "nation" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1