Calculate percentage using previous row’s data with multiple filters

Hi geminirand ,

Use this two DAXs to create measures:

summed = 
VAR _Month = MONTH(MAX('Table'[Royalty_Date]))
VAR _Book = MAX('Table'[Title])
VAR _Units = 
CALCULATE(
    SUM('Table'[Total_Units]),
    ALLEXCEPT('Table', 'Table'[Royalty_Date].[Year]),
    MONTH('Table'[Royalty_Date]) = _Month && 'Table'[Title] = _Book && ('Table'[Format_Abbr] = "Audio" || 'Table'[Format_Abbr] = "eBook" || 'Table'[Format_Abbr] = "HC" || 'Table'[Format_Abbr] = "PPB"
    )
)
RETURN
_Units

Previous = 
VAR _Month = MONTH(MAX('Table'[Royalty_Date]))
VAR _Book = MAX('Table'[Title])
VAR _Previous = 
CALCULATE(
    SUM('Table'[Total_Units]),
    ALLEXCEPT('Table', 'Table'[Royalty_Date].[Year]),
    MONTH('Table'[Royalty_Date]) = _Month && 'Table'[Book_Number] = MAX('Table'[Book_Number]) - 1 && ('Table'[Format_Abbr] = "Audio" || 'Table'[Format_Abbr] = "eBook" || 'Table'[Format_Abbr] = "HC" || 'Table'[Format_Abbr] = "PPB") 
)
RETURN
_Previous

Especially here:

Then create two more measures to refer to the above two measures:

all formats summed = SUMX(VALUES('Table'[Royalty_Date].[Month]), [summed])

all formats percentage = 
VAR _a = SUMX(VALUES('Table'[Royalty_Date].[Month]), [all formats summed])
VAR _b = SUMX(VALUES('Table'[Royalty_Date].[Month]), [Previous])
RETURN
IF(
    _b = BLANK(),
    1,
    _a / _b
)

Then put these two measures above into the Matrix's Values:

And the final output is as below:

47+35+34=116
42+29+36=107
(42+29+36) / (47+35+34)=92.24%

And when I change the slicer:

Best Regards,
Dino Tao
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