SELECT 
   d."DEPTNO" "DEPTNO", 
   d."DNAME" "DNAME", 
   d."LOC" "LOC",
   (select count(*) from wwv_demo_emp e where e.deptno = d.deptno) employee_count,
   round( (select count(*) from wwv_demo_emp e where e.deptno = d.deptno) /
      (select count(*) from wwv_demo_emp) * 100 )
      percent_of_organization
FROM 
   "WWV_DEMO_DEPT" d