Count next record in report summary for different fields

[Eric B.]

I have 30 clients with many records. The report is sorted
by client then by 4 types of transactions (buy, sell,
credit, return).

How can I count to the next client by using 30 different
fields in the report footer (not page or client footer)
thereby, giving summary information, on each individual
client, in report footer.

i.e.
(Report Footer)

field1:
controlsource=[client]

field2:
controlsource= Next([client]+1)

field3:
controlsource= Next([client]+2)