After he examined the actual tariff revenue data, he concluded that revenue decreased by about 4% from $225 million to $215 million, after the Tariff of 1890 increased rates. Irwin explains that to be due to a provision for raw sugar be moved to the duty-free list. Sugar was then the item that raised the most tariff revenue and so making it duty-free reduced revenue. If sugar is excluded from import calculations, the tariff revenue increased by 7.8%, from $170 million to $183 million.