How to get % difference in line chart with two dimensions and one expression

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I am trying to get % increase/decrease in a line chart having 2 dimensions and 1 expression. 

I get correct % values in case of one dimension, however when second dimension is added, the values are not correct for each individual line.

Making separate expressions is not an ideal way as there are many values in the second dimension.

What is the correct way to achieve the above?

Thanks

Edit : I've attached a sample file to explain better. The first chart is what I want but am getting weird % values, unlike the second chart that works fine for total value.

[JamesWilder]

A chart can take a large variety of forms. However, there are common features that provide the chart with its ability to extract meaning from data.  Within the graph, a grid of lines may appear to aid in the visual alignment of data.  When the data appearing in a chart contains multiple variables, the chart.

Official Site

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I'm sorry, what?