Solution : https://service.sap.com/sap/support/notes/178921 (SAP Service marketplace login required)
Summary : 
      
Key words : 
symptom large dataset, additional key words, relevant archiving object, object type ao, reconciliation ledger fi/, object type, reconciliation ledger, archiving cycle, rapid increase, 400 mb monthly
Related Notes : 
       
| 195480 | Simulation for document summarization in CO | 
| 189370 | Incorrect CO summarization (OKBI) | 
| 182496 | COIN: Deactivating update of reconciliation object | 
| 147766 | Document summarization in CO available as of Release 4.0A | 
| 138688 | Archiving/Controlling: table analysis |