PostgreSQL 9.3: Filter in Pivot table query

Question

Well I have this records:

  Employee_Number    Employee_role         Group_Name
  ----------------------------------------------------
  EMP101             C# Developer            Group_1      
  EMP102             ASP Developer           Group_1      
  EMP103             SQL Developer           Group_2      
  EMP104             PLSQL Developer         Group_2      
  EMP101             Java Developer          
  EMP102             Web Developer          
  EMP101             DBA          
  EMP105             DBA          
  EMP106             SQL Developer           Group_3      
  EMP107             Oracle Developer        Group_3      
  EMP101             Oracle Developer        Group_3      

Want to show the pivot table for above records in the following format:

 Employee_Number     TotalRoles      TotalGroups       Available     Others     Group_1     Group_2      Group_3
 -----------------------------------------------------------------------------------------------------------------
 EMP101                   4               3                2            2          1                        1
 EMP102                   2               3                1            1          1 
 EMP103                   1               3                1            0                      1
 EMP104                   1               3                1            0                      1
 EMP105                   1               3                0            1
 EMP106                   1               3                1            0                                   1
 EMP107                   1               3                1            0                                   1

For the above result I am using the following script:

SELECT * FROM crosstab(
      $$SELECT grp.*, e.group_name
         , CASE WHEN e.employee_number IS NULL THEN 0 ELSE 1 END AS val
    FROM  (
       SELECT employee_number
        , count(employee_role)::int            AS total_roles
        , (SELECT count(DISTINCT group_name)::int
           FROM   employee
           WHERE  group_name <> '')            AS total_groups
        , count(group_name <> '' OR NULL)::INT AS available                    
        , count(group_name =  '' OR NULL)::int AS others
       FROM   employee
       GROUP  BY employee_number
       ) grp
    LEFT   JOIN employee e ON e.employee_number = grp.employee_number
                  AND e.group_name <> ''         
    ORDER  BY grp.employee_number, e.group_name$$
     ,$$VALUES ('Group_1'),('Group_2'),('Group_3')$$
   ) AS ct (employee_number text
      , total_roles  int
      , total_groups int
      , available    int
      , others       int
      , "Group_1"    int
      , "Group_2"    int
      , "Group_3"    int);

But:Now I want to show the pivot table for the above records by filtering the Group_Name. That means if I want to show the pivot table for the only Group_Name= Group_3 then it has to show only the employee who is only belongs to the Group_Name= Group_3 not other than that.

If I want to see the employee who is belongs to the Group_3 only than it has to show me:

   Employee_Number    total_roles  total_groups   available    others    Group_3
  ------------------------------------------------------------------------------- 
       EMP106             1             3            1            0            1
       EMP107             1             3            1            0            1

Note: As you can see in the first table the employee EMP106 and EMP107 is only belongs to the Group_Name = Group_3. The employee EMP101 is also belong but he also belongs to other groups so should not appear in this table.