Count month

Hello

I have a table with the end date of my project and the starting date of them
I'd like to make a measure to count the number of project which have start during the same month from the first project in november 2015 to today

I don't know how to do that automatically,  I can do that manually with : calculate(count(endprojectDate); (endProjectDate=Date(2017;11;01)

Any idea how could I do that automatically?

Many thanks in advance