Crystal reports, using a summary field in a formula

I wish to use summary data (min and max values) from a single database field within a formula that sets the value of a new calculated field. I know summary fields cannot be used in CR formulas directly. Is there any way to overcome this issue?
I am trying to produce a chart that shows the distribution of values of the field by putting each value in a band or category. But I want to be able to determine the size of each category by using the min and max values of the entire database.

Hope someone can help