WITH t AS
(
SELECT 'A1' gbn1, 'B1' gbn2, 'C1' gbn3, 'D1' gbn4 FROM dual
UNION ALL SELECT 'A1', 'B1', 'C1', 'D2' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C1', 'D2' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C1', 'D3' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C2', 'D3' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C2', 'D4' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C2', 'D4' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C2', 'D5' FROM dual
UNION ALL SELECT 'A1', 'B1', 'C2', 'D5' FROM dual
UNION ALL SELECT 'A1', 'B2', 'C3', 'D5' FROM dual
UNION ALL SELECT 'A1', 'B2', 'C3', 'D5' FROM dual
UNION ALL SELECT 'A1', 'B2', 'C4', 'D5' FROM dual
UNION ALL SELECT 'A2', 'B3', 'C1', 'D6' FROM dual
UNION ALL SELECT 'A2', 'B3', 'C2', 'D7' FROM dual
UNION ALL SELECT 'A2', 'B4', 'C2', 'D7' FROM dual
UNION ALL SELECT 'A2', 'B4', 'C3', 'D8' FROM dual
)
SELECT gbn1
     , SUM(COUNT(*)) OVER(PARTITION BY gbn1) cnt1
     , gbn2
     , SUM(COUNT(*)) OVER(PARTITION BY gbn1, gbn2) cnt2
     , gbn3
     , SUM(COUNT(*)) OVER(PARTITION BY gbn1, gbn2, gbn3) cnt3
     , gbn4
     , COUNT(*) cnt4
  FROM t
 GROUP BY gbn1, gbn2, gbn3, gbn4
 ORDER BY gbn1, gbn2, gbn3, gbn4
;