Report and VAT output

I am currently working on report 202 Sales Document-Test.

If you go to Sales and Receivables, and then to Invoices.
On the subform pretend you have 3 items such as the following, with the VAT being what I have written below.

ITEM...........VAT
PC..................8
DVD ROM........8
CD ROM..........18

I have made in the report a Sales Header, Footer (3). and a text box with SourceExp = VATAmountLine.VAT%

How can I make this text box show the different VAT's without repeating? For the example above, I would want my output to be :

8
18

The 8 would only show up once...I just want to show the different types of the specific invoice.

can anyone help?[/b]