Projecting AWR space usage

The AWR had to be rebuilt, and at the same time new values for the retention time were set. How big will the SYSAUX tablespace grow? After some days of typical activity, I used this SQL to project the current AWR SYSAUX space usage into the future:

select q1.awr_days, q3.awr_usage_mb, q2.retention_days, awr_usage_mb * retention_days/ awr_days awr_usage_projection_mb from
(
select extract ( DAY from (max(begin_interval_time) - min(begin_interval_time)) ) +1 awr_days, count(*) awr_snaps from dba_hist_snapshot
) q1
, (
select extract(DAY from retention) retention_days from  dba_hist_wr_control
) q2
, (
select SPACE_USAGE_KBYTES/1024 awr_usage_mb from v$sysaux_occupants where OCCUPANT_NAME = 'SM/AWR'
) q3
;