Add a dynamic label to show percentage increase from the same month from last year inside an area chart

[marxsabandana]

I need to find a way to show the percentage of increase/decrease inside the label when a certain point of a graph is hovered.

For example, I hovered the point in April 2019 and has a value of 1,000,000 while in the other chart has April 2018 with a value of 800,000. The hovered point shall indicate the percent right after the value of 1,000,000. Thus the label should be:

April 1, 2019
FIELDNAME: 1,000,000 +20%