CREATE TABLE table_203_501 (id DECIMAL, "title" TEXT, "genre" TEXT, "sub\\u00addivisions" TEXT, "libretto" TEXT, "premiere date" TEXT, "place ,  theatre" TEXT)

which genre is featured the most in this chart ?
SELECT "genre" FROM table_203_501 GROUP BY "genre" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "genre" FROM "table_203_501" GROUP BY "genre" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1