Define a calculation field and divide the Total End count by the Total Time but with time converted into hours. (Time fields store time as the number of seconds since midnight)
Total End Count / ( Total Time / 3600 ) // there are 3600 seconds in an hour
Using some math skills, you can rearrange the terms to use this expression:
Total End Count * 3600 / Total Time
This calculation will return "grand totals" based on your current found set. If you need to compute a sub total type value for use in a sub summary layout part, use the GetSummary function to get the two subtotals from your two summary fields.