Line and Clustered column chart

[VPlorim]

I created a calculated measure to get an average per month for 2018 and 2019.  I am using data direct from the azure database

I need to now show the percentage decrease or increase from the average that I created

I have a line and clustered column chart but cannot figure out how to make the line the percentage of the average

I have copied my chart below

[jski]

Can you create another measure that is the difference between the average and the actual and then use that in the viz instead?

[VPlorim]

I am having a hard time doing that.  That would be ideal but I am just not sure how to format that

[jski]

What do your 'average' and 'actual' measures look like?