Conditional Measure and Average based on Page Slicer

Hi all,

I have a calculation that I had calculated on excel, but need to now write a measure to calculate it within Power BI.

Current situation:

Excel:

Power BI:

- Page slicer by date

- Gauge chart: Value based on the following formula (thank you isjoycewangFilter for Chart Based on Filter for Page )

Column Chart Value = 
var maxyear = MAXX(ALLSELECTED('Table'), 'Table'[Date].[Year])
var minyear = maxyear -2
var selectedyear = SELECTEDVALUE('Table'[Date].[Year])
var result = 
    IF( selectedyear <= maxyear && selectedyear >= minyear, 
    CALCULATE([MeasureX], ALL('Table'[Date]), 'Table'[Date].[Year] = selectedyear), 
    BLANK())
return result

 - MeasureX: Calculates the flags less "NA"

MeasureX = Calculate(
Distinctcount(Table[Conditional Flag]),
Filter(Table,Table[Conditional Flag] <> "NA"
))

I would like to move the calculation of the Flagging to Power BI. This is because I would like the average to be calculated based on the page slicer and the 2 years before, i.e. if end-date of page slicer = 2023, then years for calculation = 2021, 2022, 2023

The current flagging flags 2 out of 4 years. I would like to have the following result:

If years = 2021, 2022, 2023, then 2021 and 2023 will be flagged with sum of the year more than the average of 14.3

If years = 2020, 2021, 2022 then 2020, 2021 will be flagged with the sum of the year more than the average of 12.66

Thank you!