The council must finally adopt, not later than the first Tuesday in September, an ordinance levying upon the assessed valuation of the property in the city, subject to the provisions of this Charter, a rate of taxation upon each hundred dollars of valuation sufficient to raise the amounts estimated to be required in the annual budget, less the amount estimated to be received from fines, licenses, and other sources of revenue. They shall then deliver the assessment roll to the auditor who shall compute and carry out the amount of the tax so levied upon each parcel of property contained in said assessment roll. The corrected list for each tax shall be the assessment roll of said tax for said year, and it shall be certified by the auditor as being the assessment roll of said tax; provided, however, that within five years of the final date of adoption of this Charter there shall be an appraisal by an expert of all real property and improvements in the City of Petaluma for assessment purposes.