Use the most recent available value in forecasting formula with future dates

Hello,

I am trying to use the most recent value (date is 2017) in a formula to obtain a forecast for 2018, 2019 and 2020.

Right now, the only way I am able to get the forecast to work is to create a variable for each year of my forecast. That is to say that, in order to get the most recent value to push on into dates in the future I use:

2018 N R Forecast = 
IF( ISBLANK( [Total New R]),
CALCULATE( [Total New R], SAMEPERIODLASTYEAR('Fiscal Year'[Dates])),
BLANK())

Then, I end up with multiple variables: 2018 N R Forecast, 2019 N R Forecast, and 2020 N R Forecast.

Since I want to use the same value repeatedly for future dates, isn't there another way other than the SAMEPERIODLASTYEAR? I have tried creating a calculated column using MAX, but that did not work in the forumla.

Thanks,

Ashley