Crystal Reports (Assistance with Calculated Members in a Crosstabs Report)

Here is my Crosstab...

The first column is HOURS (1 = pm) (so on...)

Next is a SUMMARY which is Distinctcount(BaseID)
Next is a SUMMARY which is Distinctcount(Date) *Total number days within period call for

Does anyone know how to use an embedded summary or a Calculated Member to add another summary to this crosstab report that will do the following:

If Hour = 1 then 709/21  distinctcount(BaseID)/distinctcount(Date)
If Hour =2 then 725/21

I've got to find a way to calculate this average to report on a chart.
            
Total      5,281      21
1      709      21
2      725      21
3      698      21
4      689      21
5      267      21
8      70      18
9      311      20
10      500      20
11      637      21
12      675      21