select decode(GROUPING(to_char(trans_date, 'YYYY')), 1, 'All 
Years',to_char(trans_date, 'YYYY')) as Year,

decode(GROUPING(band),1, 'All Bands', band) as Band,
sum(sales_amt) as total_sales_amt
from
  (select customer_id, NTILE(4) over(order by sum(sales_amt)) as band
  from sales group by customer_id) a, sales b

where a.customer_id = b.customer_id
group by cube(to_char(trans_date, 'YYYY'), band);

YEAR         BAND           TOTAL_SALES_AMT
-------      -------        ------------------------
1999         1              13506897

1999         2              10987237
1999         3              5629814
1999         4              3328976
1999         All Bands      33452924
2000         1              20987154
2000         2              9852395
2000         3              5680923

2000         4              2984109
2000         All Bands      39504581
All Years    1              34494051
All Years    2              20839632
All Years    3              11310737
All Years    4              6313085 
All Years    All Bands      72957505