Counting values in previous period(s) DAX

Hi.

I have one column named Month Tagged which contains dates from TODAY all the way back to 2012. I have 100K of lines of data with a Month Tagged field on every line.

I do reporting every month for the previous 11 months.

All I want to do is a calculated measure that counts the amount of times each month occurs in the previous 11 months.
dax
So for May 2016 reporting I will want to cont how many time each Month Tagged occur from June 2015 to April 2016.

Any help would be appreciated

How do you tell the system you're working on May 2016? Do you have a timeline/slicer hooked up to a specific field?

The Month Tagged... is this is date, or just a number? Can you post a five line sample of that that table looks like?

Currentley I use the below excel formula to tell it the current month and then -1 =TEXT(EOMONTH(TODAY(),-1),"MMMM")

No I have no timeline or slicer hooked up

Month Tagged is in the format 05/2016, 04/2016 etc.... or if i do a FORMAT calculated column I can get it to look like May-16, Apr-16 etc.....

Example Data: