Amending Chapter 19-1300 of The Philadelphia Code, entitled "Real Estate Taxes," by providing that real estate taxes levied under that Chapter shall not increase in any one year by more than a specified percentage as the result of an increase in the assessed value of the property as returned by the Board of Revision of Taxes; by providing that if the growth in the total assessed value of all real estate in the City exceeds a specified percentage in any year, then the rate of the real estate tax will be reduced proportionately; and by restating the rates of taxation in tabular form; all under c — Open Common Ground