Count dates within months

Hi,

I feel like this should be an easy measure to write but im struggling.

I have a dataset which includes a start date. I want to count and summarise the start date by month and year. 

Data example

Required output

I have a calendar table but as im wanting to display by month and year i cant figure out how to display the date in that format without it being in text format. I then cant match the data as its date to text fields

Thanks