dba_hist_sqlstat, snap_id's 'Execution_total'

How is the figure 'excutions_total' derived (how does it come to this figure) in:

select to_char(s.begin_interval_time,'mm-dd hh24')  c1 ,a.snap_id  c2, sum(sq.executions_total) c3

from dba_hist_sqlstat sq, dba_hist_snapshot s

where s.snap_id=sq.snap_id

and s,begin_interval_time between to_date('2014/06/07 00:00:00,'yyyy/mm/dd HH24:MI:SS')

     and to_date('2014/06/07 23:59:59','yyyy/mm/dd HH24:MI:SS')

group by s.snap_id, begin_interval_time

order by c1;

I tried to look in the awr report for a select snap_id in the report, the total of executes in the snap_id does not add up to that number in the report above. Where does this number, the come from? how is it calculated? anyone have any idea?