Changing Waterfall chart format to % change

I've been tasked to change this waterfall chart to display as %.

It currently displays value change by manufacturer from left to right (in #.##M format). But I need this to show as % instead.

I presume I need to make alterations within the measure, but am struggling on how exactly to do this.

I was hoping it would be straight forward but seems more complex than initially thought. 

Any help would be much appreciated