CREATE TABLE table_39101 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Game site" TEXT, "Attendance" FLOAT)

What's the Lowest Attendance with a Game site of Riverfront Stadium?
SELECT MIN("Attendance") FROM table_39101 WHERE "Game site" = 'riverfront stadium'
SELECT MIN("Attendance") FROM "table_39101" WHERE "Game site" = 'riverfront stadium'