CREATE TABLE table_203_677 (id DECIMAL, "year" DECIMAL, "competition" TEXT, "venue" TEXT, "position" TEXT, "event" TEXT, "notes" TEXT)

what competition was his top performance ?
SELECT "competition" FROM table_203_677 ORDER BY "position" LIMIT 1
SELECT "competition" FROM "table_203_677" ORDER BY "position" NULLS FIRST LIMIT 1