show and compare calculated values in a chart/ graphic widget

[andries_bos]

I would like to show graphical representation of the calculated difference in total of different products.

Incoming					outgoing					difference
Location	Product	Description	Tons		Location	Product	Description	Tons	%	in-uit
amsterdam	D4000	Incoming prod A1	1060,8		amsterdam	D4500	Outgoing prod A2	421	50,05945
amsterdam	D4200	Incoming prod B1	62,2		amsterdam	D4523	Outgoing prod B2	420	49,94055
		Totaal	1123				Totaal	841		282

Its easy to show in a chart the totals for products for current year, ( = Sum({< Year={$(=Max(Jaar))} >} Receipt.Weight.Kilo))

but the user wants to show :

1. Difference between all four IN en OUT Products :  (where the % shows in the above tabel)

2. and  with two different products, the difference for thetwo  outgoing products should be shown. (The coloured % values in the above table is the comparison between D4500/D4523 etc...)

Amoung this example, I have a list of other/ different products to compare in the same way. I have attached a xls ans an example.

What is best practice to show this calculated values in a graphical form. : how to 'filter' the products and what sort of chart/ graphic widget should/could be used to represent these type of calculated values...

A second challenge is to show these values in time e.g. per week etc...