In addition to Andy's request for more information, I would suggest you create a table object with the data in it as well, so you can see the numbers that are being used in the chart. That way you will have a better understanding of the calculation and to see if it is accurate.
I am not sure what you mean by "but it not aggregated by years at all."
The chart is showing years across the bottom - so the amount is being aggregated by customer, for each year.
I am not sure if the aggr() function is giving you what you expect. Let me conduct some research and get back to you.
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