CREATE TABLE table_204_893 (id DECIMAL, "rank" DECIMAL, "name" TEXT, "nationality" TEXT, "time" TEXT, "notes" TEXT)

which country had the most athletes ?
SELECT "nationality" FROM table_204_893 GROUP BY "nationality" ORDER BY COUNT("name") DESC LIMIT 1
SELECT "nationality" FROM "table_204_893" GROUP BY "nationality" ORDER BY COUNT("name") DESC NULLS LAST LIMIT 1