examples/sample-model/Sales.Measures.dax

'Sales'[Total Sales] =
SUM ( 'Sales'[Sales Amount] )

'Sales'[Sales YoY %] =
DIVIDE (
    [Total Sales] - [Total Sales Prior Year],
    [Total Sales Prior Year]
)

'Sales'[Total Sales Prior Year] =
CALCULATE (
    [Total Sales],
    SAMEPERIODLASTYEAR ( 'Date'[Date] )
)