There are two ways of doing this:
1. Create 2 formulas - one for Active and one for Standby. They'll have this type of format:
if {MyTable.PassengerType} = "Active" then 1 else 0
or
if {MyTable.PassengerType} = "Standby" then 1 else 0
Sum these formulas at the group level to get your counts - they can be put in either group headers or group footers.
2. Use running totals.
Field to Summarize: Some unique field in the record
Summary: Count
Evaluate On: Every Record
Reset On: Change of group and select your account group.
Running total values only work if you put them in group footers.
-Dell