Audit - Number of concurent user by day

Hi Experts,

I need to calculate the Number of concurrent Users in our BI 4.1 SP2; I download and configure the Audit Universe from this Link.

Sample Auditing Universe and Reports for SAP BusinessObjects_4_x

http://scn.sap.com/docs/DOC-53904

Any help or idea to have number of concurrent users / by day / by month.

Thanks and best regards

ELYAE