The total market value of real estate in Altonville has steadily declined over the past four years. This decline has meant that the overall figure on which the city's property tax is based-the assessed value of that real estate-has also declined. The percentage of assessed value that was paid as property taxes to the city, however, did not change from year to year during this period.

The information above most strongly supports which of the following?

【选项】During the past four years, Altonville officials increased tax rates on other sources of revenue such as retail sales and business profits.