The cost of doing business on the Strip has skyrocketed, with casinos attempting to lure customers with more discounts and freebies amid a worsening economy, according to the Gaming Control Board’s annual report on the industry. The report suggests that Strip customers spent more on food and rooms and less on just about everything else, including gambling and drinking. Revenue fell by nearly a percentage point at Strip casinos, while the properties’ corporate expenses rose 19 percent during the fiscal year that ended June 30, compared with the same period a year earlier. Profit fell 57 percent as a result.