CREATE TABLE table_204_634 (id DECIMAL, "tour" DECIMAL, "official title" TEXT, "venue" TEXT, "city" TEXT, "date\ start" TEXT, "date\ finish" TEXT, "prize money\ usd" DECIMAL, "report" TEXT)

which series has the highest prize payout ?
SELECT "official title" FROM table_204_634 ORDER BY "prize money\nusd" DESC LIMIT 1
SELECT "official title" FROM "table_204_634" ORDER BY "prize money\nusd" DESC NULLS LAST LIMIT 1