Solution : https://service.sap.com/sap/support/notes/522889 (SAP Service marketplace login required)
Key words : 
audit trail evaluation tool considerably, deleted data records partially, log table dbtablog prior, optimize start date behavior, terms audit trail, deleted data records, log table dbtablog, oldest data record, ph-elr add-, additional selection screen
Related Notes : 
       
| 667871 | AUT_DEL: Additional deleting-procedure | 
| 572860 | |
| 549537 | |
| 536393 | |
| 531937 | AUT04: Assignment of long texts to transactions | 
| 531923 | Audit Trail: Indexes on table DBTABLOG | 
| 529676 | AUT10: Background processing / variant call |