CREATE TABLE table_203_153 (id DECIMAL, "stamp issue date" TEXT, "stamp set" TEXT, "#cards" TEXT, "card set ref" TEXT, "qty. issued" DECIMAL)

how many stamp sets had at least 50,000 issued ?
SELECT COUNT("stamp set") FROM table_203_153 WHERE "qty. issued" >= 50000
SELECT COUNT("stamp set") FROM "table_203_153" WHERE "qty. issued" >= 50000