Much read activity on sys.aud$

Hello all

We have the following audited, which of course generates a lot of audit. But we do not really understand why there is very much read activity on sys.aud$ ?? From dba_hist_sqltext and v$sql nothing weird stands out. Any explanations or ideas for further analysis?

Regrads Niels Jespersen

select * from Dba_stmt_audit_opts;

USER_NAME                      PROXY_NAME                     AUDIT_OPTION                             SUCCESS    FAILURE  
------------------------------ ------------------------------ ---------------------------------------- ---------- ----------
                                                              ALTER SYSTEM                             BY ACCESS  BY ACCESS
                                                              SYSTEM AUDIT                             BY ACCESS  BY ACCESS
                                                              CREATE SESSION                           BY ACCESS  BY ACCESS
                                                              ALTER USER                               BY ACCESS  BY ACCESS
                                                              SELECT TABLE                             BY SESSION BY SESSION