List of unused reports

Hi all,
we have an installation of Cognos with hundreds of reports; now we would like to reorganize the areas and first of all remove the unused reports.
How can I get the list of unused reports in Cognos?
Thanks
stefano

1.Direct log messages to a database.

  1. Set up a logging database and configure log messages to be sent to the database. For information about configuring log messages, see the Installation and Configuration Guide. Important: The logging database must be separate from the Content Store database.

  2. Set the logging level for audit reports.

  3. Set the logging level to Basic or higher. Do not set the logging level to Full, which will log too much information. For more information, see Set Logging Levels.
    Enable native query logging .

more detail
http://publib.boulder.ibm.com/infocenter/c8bi/v8r4m0/topic/com.ibm.swg.im.cognos.ug_cra.8.4.0.doc/ug_cra_id3354SampleAuditReports.html#SampleAuditReports