Hi Arnold
I'm not sure if you have got the answer you are looking for, so I'd let to take a step back and clarify a couple of things then reattempt the answers as provided by our community friends. As you are aware, there are two different "items" in the Service Catalog: Catalog Items and Record Producers.
When a user requests the Catalog Items, the target request (and requested items) records are created and the associated values for the variables are stored in the sc_item_option_mtom table. Reporting on this is well covered in the Wiki: Reporting on Service Catalog Variables - ServiceNow Wiki
When a user submits a Record Producer, the target record (e.g. Incident) is created where the variables are mapped to the respective fields (depending on the Record Producer's configuration). These variables are stored in the question_answer table. In this table you have the table_name and table_sys_id fields of the target record (e.g. table_name=incident) in addition to the question reference field that points to the variable. To report on this you can create a Database View for each table (e.g. a database view called Incident Variables) where you then join the respective tables (e.g. incident, question_answer, question, etc) using those fields. Following this you can then create a report on this Database View.
I hope that this is of use
