That could probably be worked out, but I would want to know more about the nature of the gradation.  Should it be an arithmetic progression of different spaces [i.e. each space larger or smaller than the next by an equal amount], or a geometric progression [i.e. each space larger or smaller than the next by an equal ratio], or perhaps something different?  How much bigger or smaller than the average size should the largest and smallest spaces be?  Etc.

How do I divide a known distance on a graduated scale? Example;