The declaration shall specify a method by which the interest attributable to each unit shall be apportioned. The apportionment may be based upon:
A. the square or cubic footage in the unit as a percentage of the square or cubic footage in all of the units;
B. the value, as that term is defined in the declaration, of the unit as a percentage of the value of all of the units; or
C. the unit itself as a percentage of all of the units in the property. The percentage interest shall change if additional units are added after the filing of the declaration.