Calculate as a %

Hello,

I am trying to calculate and display it as a %.  However, I cannot get the % to show.  Can someone please assist?

 The LeakageSum formula I used is the following:  

LeakageSum = Calculate((Sum('PBI_SI BID Leakage'[Sales.amount])-Sum('PBI_SI BID Leakage'[InvoiceTotal.amount]))/Sum('PBI_SI BID Leakage'[Sales.amount]))*100