in this situation I would switch to a sum product solution - much easier
in the long term - add up all the amounts for customer 1 and multiply by
100 then divide by all amounts for all customers - repeat for customer 2
etc.

=100*(sumproduct((A1:A1000="customer1")*(B1:B1000) )/sumproduct((b1:b1000)*1)))

assumes amounts are in column B


--
robert111
------------------------------------------------------------------------
robert111's Profile: http://www.excelforum.com/member.php...o&userid=31996
View this thread: http://www.excelforum.com/showthread...hreadid=569364