12 Months rolling average

Hi , Anonymous 

According to your description, you want to get the "12 months rolling average".

Here are the steps you can refer to :
(1)This is my test data:

To simplify the complexity of creating data, I'm using MAX instead of your COUNT here.

I create a measure to put on the visual:

Max Value(Like your Count of Value) = MAX('Table'[Value])

(2)We can add a measure like this to get it:

12 month rolling average = var _cur_date= MAX('Date'[Date])
var _last_12_month = EOMONTH(_cur_date,-12)+1
var _last_12_month_yearMonth = YEAR(_last_12_month)*100+MONTH(_last_12_month)
var _cur_year_month = MAX('Date'[Year_month])
var _t = SUMMARIZE(ALLSELECTED('Date'),'Date'[Year_month] , "value",[Max Value(Like your Count of Value)])
var _t2 = FILTER(_t ,[Year_month]>= _last_12_month_yearMonth && [Year_month]<= _cur_year_month)
return
AVERAGEX(_t2,[value])

If this method does not meet your needs, you can provide us with your special sample data and the desired output sample data in the form of tables, so that we can better help you solve the problem.

Thank you for your time and sharing, and thank you for your support and understanding of PowerBI! 

Best Regards,

Aniya Zhang

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