The cost of making improvements of the streets and alleys within any improvement district created pursuant to section 16-619 or 16-624 shall be assessed upon the lots and lands in such districts specially benefited thereby in proportion to such benefits. The amounts thereof shall, except as provided in sections 19-2428 to 19-2431, be determined by the mayor and city council under section 16-615. The assessment of the special tax for the cost of such improvements, except as provided in this section, shall be levied at one time and shall become delinquent in equal annual installments over such period of years, not to exceed twenty, as the mayor and city council may determine at the time of making the levy, the first such installment to become delinquent in fifty days after the date of such levy. Each installment, including those for graveling and the construction and replacement of pedestrian walks, plazas, malls, landscaping, lighting systems, and permanent facilities used in connection therewith as provided in this section, except the first, shall draw interest at a rate established by the mayor and city council not exceeding the rate of interest specified in section 45-104.01, as such rate may from time to time be adjusted by the Legislature, from the time of levy until the levy becomes delinquent. After the levy becomes delinquent, interest at the rate specified in section 45-104.01, as such rate may from time to time be adjusted by the Legislature, shall be paid thereon. Should there be three or more installments delinquent and unpaid on the same property the mayor and city council may by resolution declare all future installments on such delinquent property to be due on a future fixed date. The resolution shall set forth the description of the property and the names of its record title owners and shall provide that all future installments shall become delinquent upon the date fixed. A copy of such resolution shall be published one time each week for not less than twenty days in a legal newspaper in or of general circulation in the city and after the fixed date such future installments shall be deemed to be delinquent and the city may proceed to enforce and collect the total amount due and all future installments. For assessments for graveling alone and without guttering or curbing, one-third of the total amount assessed against each lot or parcel of land shall become delinquent in fifty days after the date of the levy of the same, one-third in one year, and one-third in two years.