Decrement sum of sales per year

[#1]

Hi!

I have a bar chart, with sum sales per year.

My problem is that i lose clients as the years increase. i want to make  an acomulate sum with the clients.

For example

i have 3 clients, and Sum(Sales) are 120 millons in 2015.

In 2016 i lose 1 client and the Sum(Sales) are 100millions.

The information in my table is:

Client

Client	Year	Sales
Client 1	2015	20
Client 2	2016	50
Client 3	2017	50

Something like that

Thanks for all

[Gysbert_Wassenaar]

Try this expression: sum(total Sales) - rangesum(above(sum(Sales),1,rowno()))

[#3]

Sorry but It doesn´t work, y take negative values.

The year is the year y lose de client.

what is "total sales"?

thanks

[sunny_talwar]

Gysbert's expression seems to be working here: