The off street parking requirements set forth in section 12-368 of this chapter, may be complied with providing a permanent common off street parking facility for all of the uses within the shopping center, provided that the lot contains the requisite number of spaces for each use. The total number of spaces provided shall not be less than the sum of the individual requirements; provided, however, that in no case shall the amount of off street parking area, including driveways required for ingress and egress and circulation, be less than three and one- half (31/2) times the gross floor area used for retail trades in the shopping center. (Prior code § 16-17)