Going back 2 years instead only 1

Hi there

I'm using the SAMEPERIODLASTYEAR-Function. Is there a way to get the year bevor the previous year (2016 YTD + 2015 same period + 2014 same periode)?

Currently in use:

SaleP2YTot = CALCULATE([SaleTot]; SAMEPERIODLASTYEAR('Dates'[Date]))

Thanks for any input & Regards!