Display VAT rate on invoice PDF template

Currently as part of the advanced PDF invoice template that we use, there is a invoice summary at the bottom of the invoice which lists the subtotal, VAT amount, grand total etc.  On the VAT line of this summary, we have some hardcoded text which states the tax rate applied to the invoice.  This is hardcoded but based on the bill to country of the customer.  So for example if the invoice relates to a UK address, the text that appears next to the VAT line is 'VAT (20%)'. 

Now the VAT rate has recently changed in South Africa from 14% to 15% as of 1st April.  Therefore there will still be invoices that need to have the VAT stated as 14% and some where it will be stated as 15%.  Is there a way to dynamically link the PDF form to the invoice so that it picks up the rate from within the actual invoice rather than based on the bill to currency?  I'm not concerned about the actual amount on the invoice, but the text which appears on the VAT line in the summary.