Statistics over multiple captures

Is there a simple way to grab statistics from multiple captures without having to merge them into a single capture file? In particular I want to generate statistics from Protocol Hierarchy and HTTP Packet Counter. I've been able to do this with tshark using

tshark -q -z http,tree -z io,phs -r file.cap.gz

but it only works for a single file. I've been merging them, but now my merged files are big enough to cause OutOfMemory errors. So is there a way to grab statistics over all the files like this? Or do I need to run the statistics on each capture separately and combine the results myself?

Thanks for any insights!