Forecast function is missing

I am trying to find the Forecast function in the line chart but i can't seem to find it. Anyone knows where or how I can have that option?

to provide some context I have this sample table that is extracted from a website and i have the "Report Year" having a active relationship with a Date Table. 

Plotting the line chart with the Date from Date table and the measure which is the sum of prevalence_rate but i still don't get the option