Line chart with cumulative

Hi,

I wanted to make line chart with cumulative values, divided by categories.

I have following data structure:

Date  Category Value

01-01-2019 cat1 20

01-01-2019 cat2 20

02-01-2019 cat1 20

03-01-2019 cat2 20

Regular line chart with date on axis and category in legend looks perfect, but I cant make cumulative values there, because i have live connection.

I could insert all it, by hardcoding if statements.

How can I make it generic?

Regards,

Yerkhan