Converting Field to Percentage

Hello! I am new to Power BI so this should be an easy one for you guys! I have a spreadsheet that I update manually for my team and I imported that into Power BI. I calculate a % of change from one sprint total velocity to another - I want to know the change by sprint. See below screenshot. 

In BI, that field is a uncategorized. See next two screen shots. 

Data categoryField values

I read somewhere that in BI, you can't have the formula calculating each cell (I am not explaining that right). For example, my formula for caluclating this field in excel was =([Velocity L7-Velocity L6)/Velocity L7. Can I do that in BI?

When I pull the data into a chart, it isn't useful. I would like it to be a percentage and I can add conditional formatting. 

Is there a way I can add a column or measure to convert my percent of change to a percentage? Or is there a better way to calcluate this in BI? 

Thank you! 

PS: I will be updating the excel spreadsheet bi weekly and refreshing my BI. 

data type optionspercent formatting is grayed out