internal table dynamic

I hav an internal table in the following format.

DATA : BEGIN OF gt_itab OCCURS 0,

cust(5),

adsize(3),

rate TYPE i,

END OF gt_itab.

with following entries:

<b>CUST ADSIZE RATE</b> " fields

12234 15m 220

12234 16m 230

12234 17m 420

13334 15m 620

13334 16m 720

13334 17m 670

and want them to be stored into another internal table in differnet format shown below :

<b>CUST 15m 16m 17m</b> " fields of second table Dynamic

12234 220 230 420

13334 620 720 670

Can u guys, please help me.,

Thanks n Regards,

Santosh Kotra.