KPI goal from total counted data last year

hi guys,

Need your help. I am lost.

I am new with KPI visual. So it gets me wrong when use it.

My KPI is about how many visitor (count of all row data) are coming in this year (based on the date-year slicer).

I want my goal in KPI is total count data from last year.

I got the total visitor by using this formula as the measure : 

total = COUNT(data[vehicleno])

But i don't know the formula of the goal in KPI.

Any hints? 

any help would be great.

thanks

(sorry for the bad english)