как вариант так
Measure 20 =
VAR Top6ProdCat =
FILTER (
VALUES ( 'Product Category'[Category] ),
RANKX (
ALL ( 'Product Category'[Category] ),
[SalesAmount],
,
ASC
) <= 6&&
RANKX (
ALL ( 'Product Category'[Category] ),
[SalesAmount],
,
ASC
)>1
)
RETURN
CALCULATE (
[SalesAmount],
'Product Category'[Category]
IN Top6ProdCat
)