Marcus,
Unfortunately, what is provided with the Reporting Module for Time Tracking Reports is all that you can really do. Timesheets/Time Tracking information is not opened up very well to the Reporting Module currently. We are working on rebuilding the Reporting Module but that will not be available until roughly February 2015.
Currently, the way to get this information is to use the Excel Add-In. There is an extra cost to this but this is a powerful query tool that can pull ANY data out of Clarizen and then you can use Excel functionality like Pivot Tables and graphs to create a report as desired (until the new reporting module is available).
Sincerely,
Boris Krutiy - Clarizen Success