B. The service charge rate shall be determined by dividing the expenditures determined pursuant to subsection A of this section, by the assessed fair market value, expressed in hundreds of dollars, of all real estate located within the county, city or town imposing the service charge, including nontaxable property. The resulting rate shall then be applied to the assessed value of the tax exempt property. Real estate owned by the United States government or any of its instrumentalities shall not be included in the assessed value of all property within the county, city or town.
For purposes of this section, artistic and historical significance shall not be taken into account in the valuation of exempt real estate.