If a protest against such amendment is filed in the office of the City Clerk within 14 days after the date of the conclusion of the public hearing pursuant to said publication notice, said protest being duly signed and acknowledged by the owners of 20% or more of any real property proposed to be rezoned or by the owners of 20% of the area, excepting public streets and ways located within the corporate limits of the city and located within 200 feet of the boundaries of the property proposed to be rezoned, or within 1,000 feet in the unincorporated area if the property to be rezoned is located adjacent to or outside the city's limits, such amendment shall not be passed except by at least three-fourths vote of the members of the Governing Body.