CREATE TABLE table_204_121 (id DECIMAL, "year" TEXT, "game" TEXT, "developer" TEXT, "setting" TEXT, "platform" TEXT, "notes" TEXT)

what year was the last year in which the zx plaform was used in a business simulation video game ?
SELECT MAX("year") FROM table_204_121 WHERE "platform" = 'zx'
SELECT MAX("year") FROM "table_204_121" WHERE "platform" = 'zx'