I haven't found anywhere in the Sybase database where Symposium keeps a peg count of calls by different treatment length as it does for the wait time for calls answered and calls abandonned for the different applications.
You could try to get this information from the Call by Call database, for each called answered you get the treatment time by subtracting the Event 42 (Local Call Answered) from its Event 46 (Local Call Released), and then get a count by the intervals you need.