Calculate Year To Date values

Hello everybody,

so just recently I started using Power-BI and I just can't figure out how to calculate year to date values. The problem is, I can't use the classic apprach with a date table because my data only consists of monthly values, not daily.

I've tried everything but I just can't figure it out.

This is the structure of my data:

Columns:  KPI       Month         Year         Legend

Vaues:      Sales       01             2018        Target/Actual

One remark: in the "Month" Column there the word "Target" also occurs (This is because we want an extra bar for the target to be visible in the bar charts)

I  basically just want to calculate the YTD value of actual sales based on the months. I already have a "Dates" table that contains days, months, year etc. if that is relevant.

Thank you so much in advance!!